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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
If so, you're probaby wasting your money on an "efficient" power supply.
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.
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 /.?
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/
Have electric heat? No gain.
Have air conditioning? Big gain.
Want a quite computer? Some gain.
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...
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
I haven't read the article yet. I'm about to .. but let me guess what the whole story summed up will say:
"You need to look at cost for the unit and the expected lifespan of the device as well as the expected load and and cost of the electricity to determine if you can save any money by purchasing a more efficient power supply."
I've had some machines that it makes sense to upgrade, and others that it doesn't.
Of course, if you are all about saving the planet then you'll buy the most power efficient power supply on the market regardless of price because you think its saving the planet. Of course, it may not be doing such thing since you expended more resource materials to manufacture the power supply, etc. Not to mention it might cost you more in the long run than the less expensive less efficient power supplies.
There's nothing more frustrating that having a flaky PSU. It can masquerade as any other computer issues.
If you have a UPS, high efficiency PFC power supplies are a must.
If you don't, then just do the math. 100W wasted * $0.10/kWh * 365days * 10h/day = $36.50/yr. So if you get a good power supply, with a 5 year warranty, that saves you about $100-$150 minimum in electricity alone and that is if you have the PC on average 10h/day. For people that have it on 24/7 like a server, you are looking at $250-$400 savings, never mind on replacing any crappy power supplies that last a year and die on you, possibly taking the system with it.
Even if you only save 25W in efficiency on a 24/7 system, that works out to $110+tax saved over 5 years. It pays for itself much quicker than that!
It is a no-brainer to go with high efficiency, long warranty power supplies.
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.
The better 80+ units are typically made of better components (Japanese caps, for instance) and are typically more reliable and have better voltage regulation. They convert less current to heat, reducing net heat load and ultimately cooling noise.
I'll buy high efficiency units even if the net cost is higher, which it probably is in my case. It's nice to know a heavily used 80+ unit will save its own cost in power in a few years, but cost isn't my highest priority.
BTW, Seasonic X series are outstanding power supplies.
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.
I don't know about the investment aspect, to me the more pressing issue is that the inefficient part of the power is converted into heat that now needs to be removed out of your case by blowing fans. So if you are building a rig where you intend to use a lot of high end components, you will need high power supply, and if it is inefficient it may significantly increase the heating issues inside your build and cause instabilities and shorten the life span of your components. And/or a loud noise.
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.
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
This is nice at least if you are going for a silent system, as fewer fans, cocknozzle.
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.
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
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!
Build it, Drive it, Improve it! Hybridz.org
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).
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'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]
Component quality is what matters to me, efficiency not so much.
The more you spend of PSU's the longer they tend to last.
I expect my Corsair AX850 to be still working in 5 years.
I don't expect a "super happy flower golden dragon" PSU to be working in 2 years.
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.
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.
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
Are you sure that was the only change you made in your power usage? Even with the most optimistic assumptions (70% efficient old PSU at full capacity, 90% efficient new PSU, and you have the highest electric rates in the US), I can't find a way for the PSU to pay for itself in less than one and a half billing cycles.
I'm disturbed that I was duped into reading tfa and the moronic responses to it. I hope to never see Extreme Tech website again. This is drivel.
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.
you're admitting you've been looking at kitty porn?
Sent from my ENIAC
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
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.
With Newegg putting 80+ power supplies on sale for $20 from time to time, it shouldn't take too long to make up the cost!
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.
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
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...
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.
Definitely, yes! It will open new upgrade paths, and assure your system has enough power and won't get easily damaged due to power troubles.