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Is It Worth Investing In a High-Efficiency Power Supply?
MrSeb writes "If you've gone shopping for a power supply any time over the last few years, you've probably noticed the explosive proliferation of various 80 Plus ratings. As initially conceived, an 80 Plus certification was a way for PSU manufacturers to validate that their power supply units were at least 80% efficient at 25%, 50%, 75%, and 100% of full load. In the pre-80 Plus days, PSU prices normally clustered around a given wattage output. The advent of the various 80 Plus levels has created a second variable that can have a significant impact on unit price. This leads us to three important questions: How much power can you save by moving to a higher-efficiency supply, what's the premium of doing so, and how long does it take to make back your initial investment?"
new efficiency @ load % - old efficiency @ load % = delta%
integrate over time (delta%*cost kw/hr) until result = new unit cost (solve for t)
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we could probably use a computer to figure out the answers to those questions!
"National Security is the chief cause of national insecurity." - Celine's First Law
An investment is expected to bring a net positive return over time, not bring the expected loss closer to zero.
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Bought one Antec Earthwatts long time ago. The PSU was not much more expensive than the others (good brands) so the savings are obvious. Still, the PSU is very quiet which is the main reason why I bought it.
Division of labor. You need to consider if your heating system is more efficient at heating than your power supply is.
Do you even lift?
These aren't the 'roids you're looking for.
One advantage of a more efficient PSU is that it runs cooler. This is nice at least if you are going for a silent system, as less fans are then required.
http://www.extremetech.com/extreme/143029-empowered-can-high-efficiency-power-supplies-cut-your-electricity-bill/
If you reduce the brightness of an LCD screen backlight it will also lower power consumption. Mine uses 40 watts full brightness and 20 watts dark. So if you shave off 10 watts it may nearly equal the savings of a good psu but for no outlay.
Have you looked at the price difference between different efficiencies for the same wattage? They're usually minimal. So might as well vote with your wallet and go for the highest-efficiency one. There's no telling how electricity prices will evolve over time...
To make the maths easier, lets assume you can improve your efficiency by 25% (that's huge) and assume you're loading it to 400 watts, (also huge) and assume you run it 8 hours a day, 5 days a week with 2 weeks off a year (running at full capacity).
That's 100 watts of savings, 2000 hours a year... 0.1kw X 2000 = 200kWh per year.
I pay about $0.10/kWh
You could save up to $20/year.
Reality? You'd probably see a lot less savings then that.
Higher efficiency means less waste heat coming from the power supply, so its fan can run quieter.
Antec 650W "green" power supply.
Upgraded to this from a 500W older model Antec power supply for my primary desktop, which is *never* powered off, except during hardware upgrades like replacing the power supply. My local electrical company bills every other month. The power supply cost me i believe around 80-90$ after tax and it paid for itself within one billing cycle.
Since the waste energy is converted to heat (which may increase the noise or temperature of the machine) it may well be worth the extra cash anyway.
Saving a few bucks on electricity is hardly the only reason to buy a more efficient power supply.
- Jesper
My security clearance is so high I have to kill myself if I remember I have it...
I tried to include an image of the formula using the IMG tag instead of text, but it wouldn't display. :( Any tips on how to include an image in a comment on /.?
I've never seen an image in a slashdot comment before, I think it's for our own safety.
Get your head out of your ass. Most electric heating is done with heat pumps. A heat pump pumps more heat into your house than the electric energy it consumes (that's why it's called that way). Heating by burning something is also more efficient than dissipating electric energy because you're cutting out conversion (see Carnot efficiency) and transportation losses.
And in the summer, if the AC is on, inefficient appliances make you lose double: once by consuming more electricity than they should, and a second time because the AC needs to consume energy to pump the heat out of your house.
My rental house only has electric heating. Gas comes in bottles here.
don't choose a cheap piece of shit just because it claims a higher '80 plus' certification level than a quality, name brand unit from a reputable company that might cost twice as much.
These days, 80plus PSUs are very cheap. The only things cheaper are unreliable JUNK PSUs which won't last a year. Also, because of the legal terms of using the 80plus trademark, manufacturers seem to not inflate the wattage ratings on 80plus PSUs, while you can easily find $15 "2000watt" junk PSUs.
And besides all that, I'd pay the 80plus premium just for the heat/noise reduction. Combine with a WD "Green" hard drive (or SSD), low-power CPU, and a couple low-noise fans, and you've got a very low heat and very, very quiet system.
Slashdot gets worse every day... Pipedot: News for nerds, without the corporate slant
First let's do a sanity check. Have you ever seen an image in slashdot comments?
My UID is prime... is yours?
The real embarrassment is that /. has never supported basic tags like <sup> which would allow proper math mark-up. Instead we get all manner of mangled, unreadable blobs for comments.
Slashdot gets worse every day... Pipedot: News for nerds, without the corporate slant
There's nothing more frustrating that having a flaky PSU. It can masquerade as any other computer issues.
A PSU has a power efficiency curve that looks like this. That article also explains what I'm about to summarize:
Pick a PSU that is no more powerful than you need, to keep your system in the middle of that curve, for maximum efficiency. 100% margin is more than plenty, so if your components will use 250W max, you don't need a 900W PSU. Look for something in the 500 range, or even less if you pick a good-quality PSU.
You probably won't be able to make a cost argument for maximizing efficiency, but you can build a quieter system focusing on efficiency, and it's quite satisfying obsessing over something different.
A while ago I purchased an EZ-Watt meter so see how Much power that my system was consuming. I found that my system at max CPU and GPU load consumes about 350 W of power. So my question is why would I buy a green 800 Watt power supply when my system only needs 300 W? It seems that it would be best to match the power supply to the system in order to maximize savings since the efficiency of the power supply is calculated at its maximum rating. How much power doesn't 800 Watt power supply consume when the system is using only hundred to 200-300 W? It would be interesting to connect it to a wattmeter and find the answers. I suspect that a standard power supply matched to the system power requirements would result in a larger power/money savings then buying an oversized high-efficiency power supply.
Betteridge strikes again.
09F91102 no, 455FE104 nope, F190A1E8 uh-uh, 7A5F8A09 that's not it, C87294CE no. Ah! 452F6E403CDF10714E41DFAA257D313F.
This is why "software engineer" is a term I will never use willingly. It is an insult to real engineers. Heat pumps do in fact put more heat into their hot side than they consume in work. They take heat from a low temperature resivoir and send it to a high temperature resivoir.
I've often wondered if the more efficient PSUs used better capacitors. If the extra cost needs to be offset by longer usage, will the capacitors hold up better/longer? I would guess that if the PSU runs cooler it should be an improvement in the capacitors useful life too. But the total output from a PSU decreases over time. I've used this PSU calculator over the years. In footnote 4 they mention the decreased output over time.
Not sure why this is moderated as "funny," since it's true - <img> tags can be/are used in XSS and CSRF attacks. In fact, SVG images can contain executable javascript. And let's not even mention the possibility of polyglots: http://www.thinkfu.com/blog/gifjavascript-polyglots
Noise is also a factor. High-efficiency supplies have fans that run more slowly under load, or not at all. If you're building a quiet system, this is a big deal.
Note that the peak efficiency is usually at ~50% load, so be sure to size your power supply appropriately for best results. Newegg has a calculator to help with this.
Visit the
Oh yeah, and images can be/are used for tracking as well.
Plus, if we allowed images, I'm pretty sure 90% of it would end up being porn and cat pictures.
Unless you really need it, then choose something more modest than a honking 1000W PSU. Not a frag-fracking gamer? A 90W DC PSU should have enough juice for your 65W CPU. As PSU efficiency is measured in percentage, even a 50% inefficient 90W PSU will beat a 95% efficient 1000W PSU.
And you can thank goatse.cx for that. I can't imagine looking at that gaping hole a dozen times per day.
The info I got from the article at http://www.cameralabs.com/PC_Hardware_reviews/Power_supply/Choosing_a_PC_power_supply.shtml is this ---
If your computer consumes X-watts, it's advisable to fit a PSU that can pump out almost 2X the wattage.
Muchas Gracias, Señor Edward Snowden !
As mentioned, efficiency of PSU changes over variety of conditions (load being most significant), so it's good to check reviews that do proper measurements to get the one that has good efficiency all across the range. Unlike posts above, it doesn't always fall at 50% mark. That said, good PSUs often sport high efficiency for a reason; they're made well. It'll serve you well to get a really high quality PSU if anything so it doesn't blow up on you, possibly losing all sorts of other parts in the computer, which would cost a lot more than just larger electricity bill.
the game
Can you really qualify heating done with heat pumps as electric heating? My house is heated with hot water from a gas furnace recirculated using an electric pump. By your definition of electric heating, wouldn't that make my house electrically heated? Also, aren't there transportation and conversion losses from burning something for heat just as there are with electric heating?
And in the summer, if the AC is on, inefficient appliances make you lose double: once by consuming more electricity than they should, and a second time because the AC needs to consume energy to pump the heat out of your house.
I'm not sure what method you can possibly imagine for pumping heat out of your house that doesn't consume energy.
Of course, it's summer here now.
I've never seen an image in a slashdot comment before, I think it's for our own safety.
I remember the good old days before the spam filter when every third post was an ASCII depitction of goatse and we liked it!
[Fuck Beta]
o0t!
so it probably for 99% of the people won't make sense to upgrade a power supply just for efficiency
but if for some reason you need a new power-supply anyways finding a good quality (80+ gold ..etc) unit on sale is totally reasonable.... at this point most units worth trusting the rest of your gear to are probably 80+ anyways.
in my own case i had been using a 80+ power-supply that wasn't modular and cables where a hassle to manage ... i wanted a modular power-supply and also have no intention of risking a $200 processor and $300~ video card etc to a generic / shoddy power-supply so i found the Seasonic X750 (80+ Gold ) on sale for $100~ (which if you look at newegg is cheaper than any 700-800watt fully modular power supplies currently.
since i wanted/needed fully modular 750~ish watt power-supply finding the X750 for $99 made sense as it was cheapest meeting those requirements.... the fact is it 80+ is just bonus ... seasonic's 5year warr and generally pretty good reputation for quality power supplies drove the choice more than the 80+ gold.
actually I am happy to see you, however that is in fact a banana in my pocket.
The design choices that manufacturers make in order to meet these levels of effeciency have other impacts. Active power management, cooling fans that only run when needed, and higher quality components are all good reasons to consider a higher effeciency rated PSU. My computers often run 24x7 for years on end so I tend to choose decent PSU.
Also, just as a data point, I have a 4U box running a Xeon, 32gig of RAM, many cooling fans, 3x SAS cards, an SSD, and at least 20x HDD. It has a gold rated PSU listed as 850watts. Oh yeah, integrated onboard video. Usage at the plug? With all drives spinning actively it uses right at 200watts! Less when unRAID spins drives down, none of the drives are "green". The number surprised me!
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Most PSU that do not sport the 80+ badge are outright junk that does not respect environmental and security norms in the first place, and will blow up in a variety of creative ways if you were to draw half of what is written as max wattage on the sticker. The 80+ badge weeds out most of the crap (not all though).
Perhaps the "pump" part of heat pump completely eluded you, since they do not defy the first law of thermodynamics as you seem to be implying.
Heat pumps work by having a sink source off of which they are pumping the heat from or away from. Most of the ones I know happen to be geothermal, which work because the sink which they are pumping from maintains a constant temperature year long underground. So, during the summer, the heat they can extract from that source would be cooler than the air above ground, but during the winter be hotter. They do this by extracting the heat from the source sink, rather than producing it themselves.
So in that respect, they work much like the fan does within your computer, since the air inside the case is much hotter when running than the air outside of the case. The fan can then displace that heat generated inside rather efficiently by just pushing the hotter air inside the case out, while bringing the cooler air from the room outside in without having to require an equal amount of energy to then power those fans as the equipment running inside of it, thus, like the grandparent, requiring less electric energy to power those fans than what the computer itself uses. If this were not so, then it'd make a lot more sense to completely seal computer cases, as the cooling benefit from the fans wouldn't make up for the amount of dust which they bring into the case during operation.
So the next time you're tempted to call bullshit on a well known physics principle, make sure you double check that you're not making some stupid mistake. Or else you'll end up looking rather foolish again when someone else points out how you don't know what you're talking about.
So there are a lot of factors that influence the production cost of a power supply. Some of the newer quasi-resonant and PFC-Forward designs are very good at eliminating switching losses, and are relatively cheap until you get to the switch and transformer, which are the critical loss pieces in a given switching supply design. It is justified that a 90% efficient supply costs more than an 80% efficient supply, because the component and design costs both go up.
But, whether or not you choose one can be influenced by many factors that don't necessarily have anything to do with efficiency.
First, a high-efficiency supply is going to throw off less waste heat. Lower temperatures mean components, especially liquid electrolyte capacitors, last longer.
Second, reliability. The #1 cause of power supply failure is the fan. A high-E supply can get away without a fan up to maybe 500W in a standard ATX form factor. So, your lower-power HTPC or workstation can benefit from being less noisy, and never having to worry about a fan failing and causing catastrophic failure.
Third, finally, overall power draw. If you're running a server 24/7 the power savings add up over time. If power is expensive, and your machine with its cheap-ass 60% efficient supply is drawing 500W from the wall, increasing your P/S efficiency to 90% will reduce your power consumption to 333W, saving 120kWh/month, which for me is about $15/month. That pays for the higher efficiency inside of a year.
I think will make sense to buy the 80-Plus Gold supply for $150 if you have a high-draw machine with a cheap-ass 60% efficient gray-box supply - every time.
Are you saying this would make /. somehow a lesser site? (scratches head)
I would insert a picture of a naked cat looking quizzical here, but alas, no IMG tag support.
See what you're missing?
Sent from my ENIAC
I live in (Western) Washington State, heat pumps are rare.
Seems like well less than 10 percent of heating systems.
Oil heat used to be the king here, gas or oil systems converted to gas seem to be the norm now.
Heating is the issue here, not cooling.So, maybe you you can take a break on the attitude, depending on where your head is.
---
Tried googling for percentage of heating system types in use but got nothing useful, kind of like here.
No brain, no pain.
I've been wanting to start a project; 'GlobalWarming@Home', with client software for people who want to contribute to the global warming effort.
All it would do is run your CPU/GPU full tilt, using as much power as possible to 'contribute' to global warming.
No it's not worth investing in a high efficiency power supply for your computer if you're trying to save money or the environment. Yes it's worth buying a 80 Plus Gold or Platinum power supply if you want to reduce noise as many of them now run fanless or have a fan that generally doesn't need to turn on.
[FUCK BETA 2.6.2014]
I bought a midrange power supply (Antec Gold £150 job) for my gaming rig some years ago (it was an Athlon XP2400+), which said 750W on the box. With a 4-box RAID0 and GeForce 7600GT the power draw was something like half that. It's still running.
I built an identical box around the same time for someone else. He didn't see the point of a beefcake PSU so he said to use a cheap (read: £20) 350W brick. His computer lasted a month before the caps blew and took the motherboard with it.
For me, it's less about power efficiency and more about the quality of the components used to build the thing. We're not talking plug and drool box level, we're talking about what caps are used to build those boxes.
I've lost count of the number of eMachines and Packard Bell machines I've had to practically rebuild from the chassis because the PSU blew. The commonality? Bestec and HiPro 300W bricks built with greymarket capacitors. Oh, you can buy replacement bricks of the same brands and wattage ratings these days for £10 shipped, but you'll have the same problems.
Operation Guillotine is in effect.
If people use less power through more efficient devices there needs to be less power produced. Less power production means less pollution and less greenhouse gases. Environmental issues may be a contributing factor in the selection of a more efficient power supply.
Well technically the waste heat from a power supply is 100% efficient. Any inefficiencies from it producing heat are used to power the computer.
So... Eternal Summer is to /. what Eternal September is to Usenet?
So they work well in heating a house as long as its not cold outside. Probably not so good in a real winter..
Theoretically spoken, they just need to pump against a larger gradient if it's really cold. They will still have a benefit, only less.
Now, practically spoken, there are these nasty little engineering considerations. A practical heat pump has to be built for cold climates, and the heat pump/AC combos that are popular in the warmer parts in the US aren't, and are actually capable of being slightly less efficient than a resistor if it's really really cold outside.
While GP is woefully incorrect and you're right to call him out on it, your explanation isn't right either. Heat pumps can in fact pump against a gradient, and are mostly used to pump heat from a cold to a hot place. Air-source heat pumps (ie. coupled to the outside air rather than a geothermal reservoir) are used in parts of the US to heat houses in the winter and cool them in the summer. They're also what makes a refrigerator work. A fridge pulls heat from a cold place (inside the fridge) to a warmer place (outside the fridge). The resulting decrease in entropy needs to be balanced by an equal of greater increase in entropy, which is accomplished by converting electricity to heat. Or, to avoid the thermodynamic jargon, you're pumping against a gradient, so you need to spend energy to do so. The heat produced at the back of your fridge is the sum of the heat that was pulled out of the interior of the fridge + the heat-equivalent of the electricity the fridge consumed. This is also what an A/C does. Now, if we turn the A/C inside-out, so that it pumps heat from outside to inside, then you have the kind of heat pump we use to heat our homes in the winter. The sum of the heat that was pulled from outside and the heat-equivalent of the electricity the device consumes is larger than the heat-equivalent of the electricity alone, thus the pump brings more heat into your home than a resistor using the same amount of electricity. GP suggested to generate electricity from this heat gradient, but the flaw in his thinking is that the heat pump as well as any electricity generation device he can come up with are bound by the Carnot efficiency, so you can never get more electricity out than you put in.
I covered that possibility too by arguing why heating your house by burning stuff is more efficient than by dissipating electricity. So you'll still benefit from an energy-efficient power supply.
Even compared to a 400%+ efficient heat pump? The heat pump in my lounge puts out 4.4W of heat for every watt it consumes.
How about reliability? I require a PSU that I know is going to
(1.) Not die within a year of running at 50-75% load
(2.) Not take any other components of my computer with it.
Power supply problems are the most annoying to diagnose, because the symptoms usually show up in other components (like apparent RAM corruption, HDD stuttering, etc). I would pay $50 extra for a power supply that is *not* 80-plus if it has stellar reliability, because it means I only have to build my computer exactly once. On that note, the Corsair HX series power supplies have not only stellar reliability, but also pretty much silent. I refuse to buy anything else, and you can usually them 20% off if you watch slickdeals.
Efficiency saves you money, while reliability saves you time *and* money. And time is a limited resource for some of us...
I have no tangible proof, but generally PSUs that have an 80+ certification are generally much better quality than those that aren't. The peace of mind knowing that your PSU is likely to out-last the rest of your components is definitely worth it. Sometimes having your computer fail costs real world money (or equatable in-game money).
In most cases it wouldn't be economicaly sensible, but what about common sensible? We in the first world have plenty of cash so why not spend some of it to save energy and reduce waste? Remember how Grandma hated waste for it's own sake? It reminds me of the business argument against renewable energy, "We will do that when it's cheaper than what we do now!, till then we feel quite sure the planet will hold up long enough for us all to get plenty of new toys." Admittedly, you would need to utilise the old power supply somehow to make this 'energy accounting' work.
Do you heat your house year rounds. It is often assume that removing a watt of heat costs 3-4 watts of power. So if you cool your house for 3 months of the year, and heat it for the rest, then that might be break even. There are many places where cooling is not installed, so it is not an option. There the power supply would only be beneficial if you can tolerate the heat. For example a small apartment in new york city with no colling where the daytime temperature might be 85, and the computer might bring that up to 90.
"She's a scientist and a lesbian. She's not going to let it slide." Orphan Black
Yes, and the energy wasted by an inefficient power supply is likewise 100% converted to energy. But the thing is: a heat pump can go higher than 100%: http://en.wikipedia.org/wiki/Heat_pump#Coefficient_of_performance_.28COP.29_and_lift It can do that because it's not a closed system - it pulls heat from outside (yes, even though it's colder outside) to inside in addition to dissipating electric energy.
As for the burning, well if you're lucky to live in a place of the world with a large percentage of renewable electricity, you can always argue that consuming electricity is better. But a lot of electricity in the world is generated by burning stuff, and the conversion of heat to electricity is limited by the Carnot efficiency, so right there, you're wasting more heat than what goes up the chimney at home (unless you're doing cogeneration). And then there are also the (admittedly smaller) losses caused by carrying that electricity through several kilometers of copper cables.
they do in depth reviews of psu's
http://www.jonnyguru.com/modules.php?name=NDReviews&op=Review_Cat&recatnum=13
as some people have already mentioned, bigger isn't always better
aim for the hardware you have plus future expansion
i have 1 hdd, 1 ssd, 16gb ddr3 1600, 2 radeon 6970's, amd 1100t@3.8, and 13 fans; 3 92mm for each gpu plus a few 140/120 (low speed)
running off an antec cp-850
Corsair's AX850 is a solid power supply OEM'd from Seasonic. But you can't cost justify buying one unless you have a truly ridiculous system. As of a few years ago, a good 500W power supply was already plenty to handle even three video card systems, and CPUs in particular have just reduced power requirements since. Newegg is showing me the AX850 as $189. You can get their similarly constructed 650W TX650M instead for $109. I was willing to pay whatever I had to in order to get the most reliable setup possible, but it was impossible to justify buying something more expensive than that. Computers nowadays just don't draw that much power. And if you only have one video card...anything over the good 400W power supplies in the $60 to $70 range is overkill.
Yeah, I know that, but didn't think that what I was saying was coming off unclearly or wrong. If it did to you, then I apologize for the confusion. While I have studied physics throughout high school and college, I don't handle any of this professionally, but have had some exposure to them before, and have had to explain to others before how they even can work in the first place.
Regrettably, I got mod points shortly after I posted, or else I would have avoided commenting to be able to mod up your further clarification.
It was hardly a scientific study but my electricity rates *are* the highest anywhere, and I use enough of it to get additional peak hours/overuse charges. I doubt that if you lived outside of any major metropolitan area or turn your computer off while you sleep it would take anything less than *years* to pay it off.
I tried to include an image of the formula using the IMG tag instead of text, but it wouldn't display. :( Any tips on how to include an image in a comment on /.?
Upload it to some other website and put the URL in your comment.
If you have a high efficiency PFC, a UPS of the proper design is a must. A good PFC power supply only does its job properly when fed a reasonable approximation of a sine wave.
On-line (double conversion) UPS units output a sine wave at all times, but are inefficient and usually very expensive.
A stand-by UPS may or may not have a switching time fast enough for a PFC power supply, and will almost never supply a reasonable approximation of a sine wave when running on battery (I don't recall ever seeing a design that did, anyway). Cheap as chips, so to speak, but you buy a UPS to keep you running through a brown-out or black-out, and everything works just fine EXCEPT the computer you were trying to keep running. They will keep running non-PFC power supplies, though, no problem at all.
A line-interactive has close to the efficiency of stand-by UPS, but with the benefit of always having the inverter/converter always connected to the output, so the response time should never be slower than what a good PFC power supply requires, and depending on the converter logic can output a good sine wave approximation. Unfortunately, many UPS units output what might be generously referred to as a "stepped sine wave" which is frequently closer to a square wave than a sine wave, so your cheap as chips power supply computers keep running fine, but your nice, shiny PFC power supply computers shut down.
Unfortunately, I live in China where lots of line interactive units that output reasonable sine waves are made, but the only way to buy them appears to be quantity 500+. I have yet to find a unit sold at retail in Zhongguancun (Beijing), Taobao, or 360buy that gives a good sine wave output without being an on-line unit. And, no, APC units- stand-by or line-interactive- do not produce a good enough sine wave for my FSP AU-400 (80+ Gold, happily reliable on Beijing wall power now for almost a year after my OCZ 500 caught fire... twice, fun story!) to keep it from shutting down, though I respect that this power supply may be more finicky than most. Cyberpower makes a nice unit (eg CP1500PFCLCD), but I can't get a 220V unit imported to China for anything close to a reasonable price, and carrying a 110V unit back from the USA with me would require using an external transformer defeating much of the value of having a line-interactive.
http://en.wikipedia.org/wiki/Windcatcher
It still consumes energy, but it's free energy. :-)
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you're admitting you've been looking at kitty porn?
Sent from my ENIAC
You need to set the "family filter" off! (but then you will be plagued with "families").
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That's why you don't use heat pumps much in colder climates. They're good down to about freezing or a little below, which is about as cold as it gets in winter in the southern US. For colder climates, it's better to use gas or oil. Best of all is solar. A large, southward facing set of windows can heat a house in the northern US almost by itself, needing only a little boost.
Electric heat is effective in cold climates, but expensive. It should be your last choice.
Intellectual Property is a monopolistic, selfish, and defective concept. It is "tyranny over the mind of man"
The specification and purpose for 80 plus is not to make power supplies more efficient in a way that matters to the consumer. Its entire purpose is to save the power company money. The way the specification is written for 80 Plus, it's a measure of the load factor. The power measured at the meter will be nearly the same (or in some cases higher as your real waste becomes reflected at the meter) between a PSU with a poor load factor and one with a high load factor.
"In an electric power system, a load with a low power factor draws more current than a load with a high power factor for the same amount of useful power transferred. The higher currents increase the energy lost in the distribution system, and require larger wires and other equipment. Because of the costs of larger equipment and wasted energy, electrical utilities will usually charge a higher cost to industrial or commercial customers where there is a low power factor." -- http://en.wikipedia.org/wiki/Power_factor
For a collection of technology obsessed geeks, you got conned big time on this one.
I buy the power supply that has DC rail current big enough to support my video card. If that's a 600W supply, then so be it. It's not usually a 1000W supply, unless I need like 3 big cards.
“Common sense is not so common.” — Voltaire
There is still conversion and inefficiencies in that and transport inefficiencies when burning stuff. Combustion is a chemical to kinetic (mostly) energy transfer no such transfer is 100% efficient as we want heat in this case the losses are the light and sound emitted. If burning wood one needs a transport truck to get it from where the the tree was chopped down and with gas there are pumps keeping the pipes under pressure and there are friction losses in the pipes. Finally one can never get more energy out of a system than put into it, heat pumps don't use less energy but instead they take it from somewhere else other than the electricity coming down the power line.
The long term average over time of power from my wind turbine - which is all the electricity I have - is 70 watts, or about 1.6Kw/h per day. That means on an average day I have about five hours use of my 'big' computer, provided I use no other electricity at all. To have the 'big' computer and the satellite link to the Internet running simultaneously, I have about four hours per average day. Given that I also need electricity for lighting (particularly these dark winter days) and to recharge other gizmos, the realistic amount of time I have drops still further.
Obviously, most people aren't in this situation. Most people can afford to pull ten times as much electricity as I have from the grid and not worry about it. But if you live off grid, investment in extra efficiency is a damn sight cheaper than investment in extra generating capacity.
I'm old enough to remember when discussions on Slashdot were well informed.
The problem with heat pumps is they're only good in places where it only gets 'sorta cold'. In places where it gets 'really cold', they don't work. Which is why they all have backup plain old electric resistance heaters.
I worked in a building that had a heat pump with a busted backup resistance heater, and it was effectively unheated for a good chunk of the year. We had to get portable heaters.
I have built passive-cooled machines since 2004 (or very nearly passive, with some machines having a single, huge, slow fan). The only way to make a PSU fanless is less wasted heat, or better efficiency. I don't care about a few wasted watts, when I have over half a kilowatt of computation going on, but I can't stand the noise of typical computer fans. High efficiency gear also tends to be very high quality for obvious reasons, so they last long. (I still have my first passive PSU from 2004, a precursor to the PicoPSUs.)
Escher was the first MC and Giger invented the HR department.
That's true. They do only work down to about -25C. I've never seen one with a traditional heater built in, but I don't live in a country where it gets that cold.
You can run a hydronic furnace off your hot water tank, with a coil in the blower to pump heat through HVAC.
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In Sweden, electric heating is illegal because it's inefficient. "Even with a 100% efficient electric heater, the amount of fuel needed for a given amount of heat is more than if the fuel was burned in a furnace or boiler at the building being heated. If the same fuel could be used for space heating by a consumer, it would be more efficient overall to burn the fuel at the end user's building."
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What the hell is a resivoir?
"There can be little doubt that union activities lead to continuous and progressive inflation." F. A. Hayek
In a perfect world, yes, but it doesn't account for wear over time on the PSU itself or real-world scenarios. If you pick a PSU to work at 90% load during peak usage, that PSUs aging will put it at 100% or more in 4 years, drastically aging the supply. Its like the power stations in Sim City, their output degrades over time. It also ensures the PSU fan is running near the top end of its spec and will burn out faster and removes the ability to upgrade to higher powered components in the future without a new purchase. The optimal purchase point is between 60-80% max load for these reasons.
I haven't seen anyone mention this, but an important factor with quality PSUs isn't so much your power bill but more the component wear in your systems. Efficient well-rated PSUs have much more stringent voltage variances as well as less problems with vdroop and such. Inconsistent or inadequate voltage is the #1 reason the parts in your systems wear over time. A well made power supply goes a long way into improving the life of your components.
I'm in the process of planning an Off Grid Solar Powered home and am hoping to find an 80 plus 150w PSU for a new build. If needed, I could possibly go with a 160w Pico PSU (12v input) for the damn thing. Migh be better as I can then push the 80 percent loading that I want for the new system that's based on an ITX board and a Xeon E3-1245v2. That's a 45w CPU with the IGP 4000 onboard. Good enough for me and runs Linux quite well. Total planned system load is 120w between the RAM, 3x 2TB Drives, 24GB SSD (board has an M-Sata slot for it) and the Burner.
As part of my plan to fit my power demand into the 30A/230V (5kw) invertor limits, I'm going with Digital Convergence and adding a Hauppauge TV Tuner/Video Capture card while underclocking the CPU by 80 percent in the bios. This wont affect video performance while cutting the CPU load down to 10 watts or less and yes I do know what that means in performance as I'm current using an AMD x2-240 Regor. Performance should be 500 to 1000 points better at the underclock I'm planning while using far less power and since I'm not an extreme gamer, the video performance will be fine (web, email, some flash games) as all of my games require Win9x and most run better under WINE anyhow.
Mod me up/Mod me down: I wont frown as I've no crown
Can you really qualify heating done with heat pumps as electric heating?
Yes.
My house is heated with hot water from a gas furnace recirculated using an electric pump. By your definition of electric heating, wouldn't that make my house electrically heated?
In your case the pump is not changing the temperature of the water. It's the gas furnace that's heating the water so it's a gas heater. In the heat pump case it's the electricity driven pump that heats whatever fluid is being used. So they are electric heaters.
Also, aren't there transportation and conversion losses from burning something for heat just as there are with electric heating?
It depends how the electricity is generated. But for most cases (coal, fuel, gas, even nuclear) you incur the same kind of extraction, refining and transport costs that you would get when you get gas or fuel delivered to your house (just a bit less because in bulk). But on top of that electricity production wastes about 60% of the heat right in the power plant(*). So you then only get to convert the remaining 40% or less to heat your house.
(*) The most recent and advanced plants that use a combined cycle manage to only waste about 45% of the heat but it's not the majority of the installed production capacity by far. Co-generation plants do better but only because they combine heating buildings with producing electricity. And they cannot heat individual houses (cost issue).
I'm not sure what method you can possibly imagine for pumping heat out of your house that doesn't consume energy.
You missed the point by a wide margin. Re-read the original message carefully.
Get your head out of your ass. Most electric heating is done with heat pumps.
Please provide sources and figures because from where I stand it really does no look that way. There's a report that says heat-pumps account for only 10% of the market, electric furnaces for 12% and various fossil fuels 62%. And that's for the US which I expect to have more heat-pumps because a bunch of them are probably reversible air conditionners. In other parts of the world I would expect the heat-pump market share to be much smaller unfortunately.
Most electric heating is done with heat pumps.
Citation strongly needed. I've only seen two or three heat pumps, ever, and those were in brand new and very expensive homes. Perhaps they're popular where you are, but I am extremely skeptical about heat pumps being remotely near a majority of electric heating units.
Dewey, what part of this looks like authorities should be involved?
First let's do a sanity check.
Sorry, my sanity check bounced. Insufficient sanity, or something like that.
I would try a reality check, but that account has been missing for some time.
Great civilizations have lived and died on false theories. Don't mess up mine with a few facts.
Higher quality PSUs will provide stable voltage and current with much less ripple than low-end PSUs. Furthermore, you get goods like overcurrent protection, modular cabling and, if you choose wisely, low noise. In my opinion, a high quality PSU is a critical component and helps you get a longer life from your components. For example, a Seasonic G-550 80+ Gold can be found for $90 and it should keep almost any user happy. I'm not saying you should get it for the Gold rating, but for the overall quality...
I apologize if my reply was a bit harsh. Being a professional scientist myself, I seem to have lost at least some of my ability to simplify matters for the sake of broad understanding, or recognize it when others do. And indeed, what you said was strictly spoken not wrong, it just wasn't the complete picture or the point I was trying to make.
Switchmode power supplies are least efficient at low power levels - sometimes shockingly so. The old pre-80PLUS supplies were sometimes 50-60% efficient.
Please help metamoderate.
Get your head out of your ass. Most electric heating is done with heat pumps. A heat pump pumps more heat into your house than the electric energy it consumes (that's why it's called that way). Heating by burning something is also more efficient than dissipating electric energy because you're cutting out conversion (see Carnot efficiency) and transportation losses.
And in the summer, if the AC is on, inefficient appliances make you lose double: once by consuming more electricity than they should, and a second time because the AC needs to consume energy to pump the heat out of your house.
Where I lived, the temp drops below 0F at which the heatpump is running at near zero percent efficiency. Actually, at 10F, I disable the heat pump and rely on electric element heating.
Now I live in an older home with radiators and hot water in circulation. The hot water is supplied by two electric boilers. The circulating water temperature is inversely proportional to the outdoor temperature. Above freezing, the water is luke warm. At 10F, the water is around 140F. and colder (5F) it sits at a max of 165F. For safety, that is also the upper limit.
Leslie Satenstein Montreal Quebec Canada
Perhaps the "pump" part of heat pump completely eluded you, since they do not defy the first law of thermodynamics as you seem to be implying.
Heat pumps work by having a sink source off of which they are pumping the heat from or away from. Most of the ones I know happen to be geothermal, which work because the sink which they are pumping from maintains a constant temperature year long underground. So, during the summer, the heat they can extract from that source would be cooler than the air above ground, but during the winter be hotter. They do this by extracting the heat from the source sink, rather than producing it themselves.
So in that respect, they work much like the fan does within your computer, since the air inside the case is much hotter when running than the air outside of the case. The fan can then displace that heat generated inside rather efficiently by just pushing the hotter air inside the case out, while bringing the cooler air from the room outside in without having to require an equal amount of energy to then power those fans as the equipment running inside of it, thus, like the grandparent, requiring less electric energy to power those fans than what the computer itself uses. If this were not so, then it'd make a lot more sense to completely seal computer cases, as the cooling benefit from the fans wouldn't make up for the amount of dust which they bring into the case during operation.
So the next time you're tempted to call bullshit on a well known physics principle, make sure you double check that you're not making some stupid mistake. Or else you'll end up looking rather foolish again when someone else points out how you don't know what you're talking about.
=== We had a Ground source HP. Three wells of 100foot depth. It worked well for two years. but the ground shifted, the pipes got pinched, and the result was "no heat". The cost to re-bore the wells was too much. So we switched to an air exchange based heat pump. In summer, the cooling was redirected to water exchange coils with the swimming pool, which received the heated water while we a/c'd the house.
For the rest of your article, it makes sense to me
Leslie Satenstein Montreal Quebec Canada
I know what a heat pump is, yes. I also know what it isn't. One of the things it isn't is magic. I see a lot of people try to make claims that they're somehow more than 100% efficient. That's just an accounting trick. Using the same trick, my gas heating system, seen as a system that uses an electric pump that pumps hot water around my house, is more than 100% efficient as long as you ignore where the heat is coming from.
My point is that a heat pump isn't magic. It requires specific conditions to function. Any magical super-efficiency it displays isn't actually efficiency, it's just taking advantage of latent energy in the system.
Can you really qualify heating done with heat pumps as electric heating?
Yes.
My house is heated with hot water from a gas furnace recirculated using an electric pump. By your definition of electric heating, wouldn't that make my house electrically heated?
In your case the pump is not changing the temperature of the water. It's the gas furnace that's heating the water so it's a gas heater. In the heat pump case it's the electricity driven pump that heats whatever fluid is being used. So they are electric heaters.
In my case the pump actually is changing the temperature of the water by moving it through heat exchanging coils in the gas furnace. If your statement "it's the gas furnace that's heating the water so it's a gas heater" holds true, then, since in a heat pump system it's the outside air heating the working fluid, a heat pump system should be called an outside air-based heater, not an electric heater. The heat pump is just moving heat around, just like the water recirculation system in my gas furnace based system. You seem to have missed my point entirely, then essentially restated my point in your own words in your post.
Also, aren't there transportation and conversion losses from burning something for heat just as there are with electric heating?
It depends how the electricity is generated.
Ok. Here I'm really confused. If you're arguing against my point (which was that the original post statement that "Heating by burning something is also more efficient than dissipating electric energy because you're cutting out conversion (see Carnot efficiency) and transportation losses" was ignoring that other methods also have conversion and transportation losses), why does it matter how the _electricity_ is generated? The original poster was the one claiming that electricity generation has transportation and conversion losses and that heating by burning something does not. I was arguing against that by point out that other methods also have those losses. How the electricity is generated is irrelevant to my argument, even if you're positing a method of electricity generation that leads to no conversion or transportation losses.
But for most cases (coal, fuel, gas, even nuclear) you incur the same kind of extraction, refining and transport costs that you would get when you get gas or fuel delivered to your house (just a bit less because in bulk). But on top of that electricity production wastes about 60% [wikipedia.org] of the heat right in the power plant(*). So you then only get to convert the remaining 40% or less to heat your house.
(*) The most recent and advanced plants that use a combined cycle manage to only waste about 45% [wikipedia.org] of the heat but it's not the majority of the installed production capacity by far. Co-generation plants [wikipedia.org] do better but only because they combine heating buildings with producing electricity. And they cannot heat individual houses (cost issue).
But the extraction, refining, and transport costs aren't non-existant as the original poster was implying. Also, furnaces aren't 100% efficient either. Some of the newer ones are pretty impressively efficient, but a good portion of the installed base of furnaces dump quite a lot of heat outside in their exhaust gases. In any case, we can keep drawing the circle wider and wider. Eventually we can get to how incredibly inefficient fossil fuels are because the equivalent amount of energy input from solar radiation to end up with a joule worth of natural gas was probably thousands of joules worth of solar energy. Then we can move on to the energy efficiency of photosynthesis and of the sun itself, etc. etc.
I'm not sure what method you can possibly imagine for pumping heat out of your house that doesn't consume energy.
You missed the point by a
Theoretically spoken, they just need to pump against a larger gradient if it's really cold. They will still have a benefit, only less.
Now, practically spoken, there are these nasty little engineering considerations. A practical heat pump has to be built for cold climates, and the heat pump/AC combos that are popular in the warmer parts in the US aren't, and are actually capable of being slightly less efficient than a resistor if it's really really cold outside.
Almost all Heat Pump systems include built in electric heaters. They are called Overload Heat or Emergency Heat. They switch on if the inside temperature is about two degrees below the setpoint of the thermostat, so avoid moving the thermostat up too much at one time in the winter. Or you can switch them on manually. They are sort of like baseboard heaters, basically. A little more efficient than a resistor, they have better impedance matching.
In my case the pump actually is changing the temperature of the water by moving it through heat exchanging coils in the gas furnace.
Hence it's not the pump that heats the water, it's the gas furnace's exchanging coils.
The heat pump is just moving heat around, just like the water recirculation system in my gas furnace based system.
You don't know how heat pumps work. In a heat pump it's the pump itself that heats the fluid by compressing it. There are then two exchangers, one to heat the house and one outside to return the now very cold fluid back to the outside temperature.
Also, aren't there transportation and conversion losses from burning something for heat just as there are with electric heating?
Ok. Here I'm really confused. [...] The original poster was the one claiming that electricity generation has transportation and conversion losses and that heating by burning something does not [...] why does it matter how the _electricity_ is generated?
While your argument about the extraction, refining and transportation losses was correct, you missed the point of the original poster which is that the big source of inefficiency for electricity is in its production from fossil fuels (as explained in my post). That's what makes the "fossil fuel -> electricity -> toasters -> heat" chain so bad comparted to '"fossil fuel -> heat". It's interesting to note that replacing the 'toasters' by heat pumps is just enough to get one back to roughly the same efficiency as using fossil fuels for heating directly.
And the method of production is important because in the case of photoelectric, wind, and hydro there is quite obviously no wasted heat in the electricity production. Also it's not as if you could cut out the electricity step to heat yourself directly from wind or hydro (in the case of solar you actually could to some extent but the efficiency gain is not that big). Of course in that sense it would still make sense to use heat pumps to get more out of your electricity.
You do have a point that not all boilers are of a modern efficient design. However even conventional designs are 70-80% efficient, which you have to compare to the fossil fuel -> electricity production step alone which is typically only 35-40% efficient, and still only 60% efficient in the very most advanced plants.
In any case, my principal gripe was the whole question of heat pumps, including the bizarre claim that most electric heating is done with heat pumps. They're expensive to install and not very widespread and lots of people supplement their heating with various types of portable heater making that a very dubious claim.
I quite agree with you on the part of heat pumps not being more expensive to install and not that widespread. I'm pretty skeptical about your implication that heat pumps must be supplemented with portable heaters. Seems like an incorrectly dimensioned installation or people getting conned by crooks.
In my case the pump actually is changing the temperature of the water by moving it through heat exchanging coils in the gas furnace.
Hence it's not the pump that heats the water, it's the gas furnace's exchanging coils.
I know it's the gas furnace that's heating the water, just it's the outside air heating the working fluid with a heat pump.
The heat pump is just moving heat around, just like the water recirculation system in my gas furnace based system.
You don't know how heat pumps work. In a heat pump it's the pump itself that heats the fluid by compressing it. There are then two exchangers, one to heat the house and one outside to return the now very cold fluid back to the outside temperature.
Sigh. Clearly you're the one who doesn't know how heat pumps work. In a heat pump, the pump raises the _temperature_ of the fluid by compressing it. That's not the same thing as heating it. The majority of the heat (obviously there's going to be some smaller amount of heat generated by the electric pump itself as well, just as with my gas furnace) is coming from the outside. The whole point of the system is to ensure that the working fluid is hotter than the inside air while inside so that heat flows from the fluid to the air and that the fluid is colder than the outside air while outside so that heat flows from the outside air into the fluid. I am pretty sure what you're failing to grasp is the fundamental difference between heat and temperature.
Also, aren't there transportation and conversion losses from burning something for heat just as there are with electric heating?
Ok. Here I'm really confused. [...] The original poster was the one claiming that electricity generation has transportation and conversion losses and that heating by burning something does not [...] why does it matter how the _electricity_ is generated?
While your argument about the extraction, refining and transportation losses was correct, you missed the point of the original poster which is that the big source of inefficiency for electricity is in its production from fossil fuels (as explained in my post). That's what makes the "fossil fuel -> electricity -> toasters -> heat" chain so bad comparted to '"fossil fuel -> heat". It's interesting to note that replacing the 'toasters' by heat pumps is just enough to get one back to roughly the same efficiency as using fossil fuels for heating directly.
It seems to me that the point of the original poster was that "heating by burning something is also more efficient than dissipating electric energy because you're cutting out conversion (see Carnot efficiency) and transportation losses". I don't think I missed anything from that single sentence. _My_ point was that, in fact, you aren't cutting out conversion and transportation losses. Generally speaking, it is more efficient, when all you want is heat, to burn something on the spot than to burn it in a central location, convert the heat to electricity, then use that electricity to generate heat in a remote location. I certainly never argued that it wasn't. I only argued that conversion and transportation losses still applied. I should also add that neither you nor the original poster have provided any proof that in situ burning will always be more efficient in every case. There are certainly a lot of variables involved.
And the method of production is important because in the case of photoelectric, wind, and hydro there is quite obviously no wasted heat in the electricity production. Also it's not as if you could cut out the electricity step to heat yourself directly from wind or hydro (in the case of solar you actually could to some extent but the efficiency gain is not that big). Of course in that se