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Building an Energy Efficient, Always-On PC?
An anonymous reader asks: "Like many readers, I find it necessary to leave my home PC running 24/7, for things like web or FTP servers, BitTorrent, or simply to make sure I don't miss any messages on IRC or my instant messaging client. It has been about 3 years since I built my current PC, and keeping it running all the time uses a lot of juice. With my next PC, I would like to do what I can to keep the power-consumption to a minimum, without sacrificing processing power or other features. What should I look for when choosing components for my PC, and what other ways are there to keep the power consumption down?"
Use two PCs. One small Via Epia 700mhz to do your webserver and bit torrent, and another PC with whatever spec you desire to use when you need to do processor-intensive stuff.
If they're networked, you can just as easily copy files over when you need them, or stream media across.
Using an LCD monitor instead of a CRT will drastically cut your power usage. Turning off the monitor while not at your computer will help as well, instead of just letting the screensaver run. The monitor can consume more power than the PC itself.
I just recently bought a Kuro Box for exactly the same reasons - low power, low noise, always on. You can load it up with Gentoo or Debian, so you can do bittorrent, ftp, http, etc. And it's cheap!
The only downside is that it's headless, but for me that wasn't an issue. If that really bugs you, you can set up a vnc server on it and graphically steer it from your PC.
Check out the kuro website. It has links to their wiki and forum.
For off-the-shelf desktop use, it's hard to beat the Mac Mini. Core duo, notebook hard drive, notebook optical drive, draws like 50 watts at idle. I hear the Acer L320 is going to be similar. No graphics in the Mini, but maybe there will be in the Acer. Good graphics cards are pretty much guaranteed to have high power consumption these days; I'm not sure if you can idle them down.
For light-duty serving, I've been very happy with the latest round of VIA boards (and I've heard the slightly cheaper Jetway variants work just as well). I have an EPIA EN12000EG fanless board running in one of those $30 mini-tower cases from Fry's (or something). The board draws something like 13 watts at idle, and 25 under load. This includes the CPU, RAM and chipset. If you can spin down the hard drives, they'll only be a few watts more, and adding in the PSU inefficiency, it'll be maybe 40 watts AC.
If you just want to serve stuff, you can toss in a 2.5" SATA hard drive (or two, for RAID) and no optical, and fit the whole thing into a case smaller than a Mac Mini, for a lower price than the Mini, with less power consumption than a Mini, even with 2x160GB notebook drives. Or you can put in an optical drive, and it'll be slightly bigger than the Mini.
I've used one of the previous round of these as a desktop machine. Its audio is decent, and as long as you're mostly browsing the CPU is fast enough (compile jobs are slow, but they're much more tolerable with the new C7 proc). The integrated graphics suck, so you won't be gaming on it.
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A laptop is already constructed to use as little power as possible, so for non-performance critical tasks, it would probably be quite useful for an always-on server. Built-in UPS is also handy, and it can be tucked away in some closet without taking any room, while still having an emergency keyboard and screen if you need to perform administration tasks on it.
For storage, a couple of USB-drives would be useful, I bet they don't draw much more power than the drive itself.
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Check out your underclocking options on your current machine; I found that Linux's 'ondemand' cpufreq policy governor made a real difference on my machine: http://parseerror.com/~pizza/cpufreq.html You can also check around in your BIOS to underclock your machine; but the disadvantage there is that the change is permanent; with Linux's CPU governors and a modern CPU your machine runs at full clockspeed only when the cycles are needed; I believe Windows has similar options.
Buy yourself a used Pentium-M based laptop. If you don't need to actually use the computer directly, buy one with the screen broken, which tends to make for some darned cheap laptops. You can hook up a monitor to it, which is how you'll put your OS on it. (Remember, laptops have mouse ports, USB ports, and display, so you can use them as a conventional computer just fine, and most laptops have the graphics chips to drive a higher resolution that their native LCD resolution.) The money you save on buying a cheap laptop like that make up for a lot of power bill, especially with the broken screen bonus.
Get the model number of the laptop in advance, cross-reference that with the chip that it uses, then find the power consumption for that chip if you want to double check. I hear the later-model ones are (surprise surprise) more efficient, but they're all pretty good AFAIK.
As somebody else said, the built-in UPC isn't bad, and a Pentium M will have all the power you need for non-floating-point functions; any Pentium M can handle even a moderately-sized website if you wanted.
My home PC server, which I left on 24x365 for email, backup, etc, ended up costing me well over $150 per year in electricity just for the PC (no periferals, monitor, or anything else).
Noticing this cost, I compared a bunch of Macintosh and PCs, as you can see in this article on PC and Mac electricity use.
As you can see, it's pretty easy to see that the cheapest devices can end up costing more in power alone.
If you plan to run an electronic device close to 24x365, factor electricity consumption into your purchase decision. Also factor in devices like cable modems, wireless routers, and so-called "sleeping equipment" - in combination, they can easily put another several hundred to your electricity bill every year. I use an X10 "appliance" controller to truly switch off idle equipment.
My total monthly electric consumption these days is well under 100 KWh.
A good option is to get a cheap virtual host. You get root, install what you like, run what you like, and it uses less power - none of yours - because there are several mostly-idle virtual machines on the same host.
Disk space is relatively expensive, and this may not be an option for you if by 'BitTorrent' you mean 'fill up my 500GB hard drive'.
As others have pointed out, if you can find an obsolete laptop, and just dedicate it for your 24/7 applications, that's going to be by far the most energy-efficient solution.
Get a Kill-A-Watt, so you can actually measure how much power various things are using. Until I got one, I had no idea that my computer's speakers were drawing 12 W all the time, even when the computer was shut down.
2.5" hard drives are more energy efficient than 3.5" ones. You need an adapter cable, and also an adapter to mount it in a standard desktop PC's cage. A 2.5" drive is more money for the same storage, but all hard disks are ridiculously huge for most people's needs these days.
Get an 80PLUS rated power supply. The 80PLUS thing means that not only is it efficient, but it's also made in a more ecologically friendly way, without lead, etc. I've heard a lot of conflicting claims about how you should choose the capacity of your PS compared to the power your machine uses. Some people say a switching PS is most efficient if you run it near its maximum capacity, and others say it's most efficient at 50%. I came across something on usenet recently where they actually collected data, and they found there really wasn't any clear relationship. It's dangerous to get a PS that's not rated high enough, because your machine may use an unusually large amount of power during the boot process, and it may boot unreliably if your PS isn't rated high enough.
Try to get all the ACPI power management features of your machine working. Unfortunately, that can be easier said than done. Many BIOSes default to only doing S1 sleep mode, which hardly saves you any power at all. That's because a lot of older hardware can't handle S3.
For your mobo, choose something with integrated video, rather than using a video card. If you're into gaming, this is yet another good reason why you don't want your always-on machine to be the same as your main machine you use all the time.
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Turn the monitor off when you aren't using it. An LCD monitor is more energy efficient than a CRT.
Buy a low-end video card. The high end cards are energy hogs.
Use a CPU that you can scale back operating frequency on using CPUSPEED etc when the machine is idle.
Don't buy more CPU speed than you need. Consider buying a low power version of the CPU you are getting.
Consider a motherboard that you can use a portable CPU on.
Buy the smallest feature size CPUs. They are usually more energy efficient.
Use smartd etc. to spin down your hard drives. Right now that usually means IDE drives - spinning down
SATA drives on Linux can be a challenge - it depends on kernel & drivers. Each hard drive = 10 watss
Don't install more RAM than you need.
Get a motherboard that allows you to turn off unneeded stuff like serial ports etc.
Buy an efficient power supply.
Use something like the Killawatt power meter to measure your results.
Switch to compact flourescent bulbs!!
Do all this and you should be able to get into the 60-70W idle range. Since 1W-year
=$1 that is $60/year.
The flourescents will save you at least another $100/year.
Well, the OP didn't say whether he was interested in low power in order to save on his electric bill, or for ecological reasons, or both. But you're right, it's not necessarily ecologically sensible to buy new hardware. In my area, the garbage company runs a disposal site for hazardous household waste, and when you go there, you see big stacks of computers. They have a program where if you ask, you can take computer hardware for free. For someone who really wants to do a favor to Mother Earth, it might be a very sensible way to pick up a case, a CD drive, and a hard disk. If there isn't anything like that in your area, chances are you can get those parts pretty darn easily at a garage sale. I picked up a really nice CRT recently at a garage sale for $10. I put it on a machine at the school where I teach that doesn't get used very often, so the electricity isn't a big issue. It sure beats dumping that same CRT in a landfill.
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Optimizing for low noise and cost based on off-the-shelf parts led me to this setup. It isn't the lowest power setup I can imagine, but noise and power are directly proportional in most cases. My goal was a very low noise, low cost always-on headless server running Linux with fault tolerant storage, at least one Gb NIC and enough processor and RAM to use for common development tasks. Based on measurements performed here and some guess work I estimate this is pulling 40W at idle and I can't hear it a beyond a meter.
MB: ASUS M2NPV-VM. AM2 socket with on-board Nvidia video, SATA etc. Not running a discrete video card is a large power savings.
CPU: Athlon 64 3500+ AM2 Lima core. This is a recent single core CPU from AMD. Easily obtainable from Newegg et al. The nice thing about it is the low TDP of 45W. This approaches portable CPUs while not costing so much. Stable at 1.2V (perhaps lower if I tried) and works well with cpufreq.
Case: Antec NSK3300 MicroATX. Small and quiet. Uses a high efficiency 300W power supply with a non-standard form factor. I doubt this machine can pull enough juice to get the fan moving at full rate. It's silent 99% of the time.
The rest: 1GB of "value ram", a pair of quiet 250GB WD disks and a Intel Gb PCI NIC I got somewhere. If you want to save more power run 1 disk, cut the RAM in half and don't add a fast NIC. Probably just under 30W at that point.
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- Strip down the hardware. Having another PC is a good place to start, that way you can run a headless server. Disable things you don't need in the BIOS. If your stuff isn't CPU-heavy, consider using a Pentium 2. They can run fanless, which is a nice thing to have in any case. If you can live without optical/floppy drives, disconnect those too.
- Tweak the kernel. cpufreq is quite good, works on a lot of processors and doesn't have much of a performance impact. Remove or modularise any hardware drivers you don't need, since the kernel might decide to keep them powered off if it can't use them. Also enable performance tweaks like DMA in the disk/network stuff.
- Don't run unnecessary software. More unused RAM is more disk cache. Read the documentation on Linux's laptop mode setting too - you can make it force the hard disk to stay powered down and only write every few minutes. If you can, just skip the hard disk altogether and run everything from tmpfs.
If you're still not satisfied, you could try some more extreme methods like disconnecting indicator LEDs.Sorry dude, Core 2s do NOT have significantly lower power consumption than AMD processors.
And even when they do, it is not so spectacular when you factor in the lack of a memory controller. (I like the Core 2, hate the P4)
Sorry, this is a COMPLEX subject. How so? Intel and AMD measure Power needs by a different yardstick. AMD makes many parts, has two different processes, and even on the same process has varying power needs.
The AMD 65nm desktop chips use VERY LITTLE power, often kicking the butt of the core 2 duo, especially at idle.
If you really want to save power on a powerfull x86, you undervolt/underclock a 3600x2 65nm chip. At this point, you will worry much more about the power consumption of your Power Supply, Video Chipset and Hard Drive.
As some have suggested, Plug in a large Flash memory device for files accessed but not updated regularly, spin down the HD after a time delay(HD's have a finite number of start ups), look for an efficient supply, and look at the newer AMD integrated video chipsets.(I think you will find these chips consume much less current than others)
I'd like to echo some of the above points. I was making a NAS server that was to be on 24-7.
1) Dump the high performance GPU. A cheap PCI video card saved me 50W.
2) Seasonic makes some nice 80% efficiency PSUs. Well worth it.
3) Turn off integrated peripherals in the BIOS. Are you using the Parallel ports and serial ports? Lower the bus frequency if you can.
I found that a cron job to turn off the CPU at midnight, along with the auto-turn on timer in the BIOS set to 7:00 also worked quite nicely.
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Take a look at Silent PC Review. Although concentrated on silent computing, any power usage produces heat requiring fans -- so they spend a lot of time worried about power/heat as well. The site is focused on building your own pc, so they do a good job reviewing components, 2.5 in disk drives, etc.
I'd agree with your points about the cost of making a new machine versus the savings; but instead of saying don't bother I'd recommend playing with the software a little. Lots of people have "24/7" servers at home for the same applications, but how many people actually use them 24/7? With me it is more a case that I want access 24/7 even if I just use it a few hours a day on average. Have a look at a hibernation kernel and WakeOnLAN. If you can bring the server up to a good point remotely with just 30sec latency then the real power saving is having it shutdown 80% of the time. Using a longhaul governer and scripts you can ensure that it stays up when it needs to (ie during a bittorrent download) but then shuts down when there are no active processes on the system.
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modprobe cpufreq_ondemand
/usr/bin/cpufreq-selector -g ondemand
now tune the up and down thresholds to your liking in the /sys/devices/system/cpu/cpu0/cpufreq/ondemand/* "files" and you're good to go.
Also, for Athlon64 and Opteron CPUs you really should enable clock divide in halt to save even more. For instructions on that read opteron-powersave.txt. (some BIOSes enable it by default, others do not)