Tuesday, May 23, 2006
Tips on desktop config for minimizing power consumption
From Slashdot
How did you do it? Which components did you choose, and what tools are available to test things like power consumption and heat output?
Just a little meta-comment first... If you log in to post, you can have Slashdot tell you when someone replies. But since you asked, I'll presume you plan to check back in the near future. :)
For measurement, I use a simple kill-a-watt meter. WONDERFUL little toy, and pretty cheap. Unless you have access to dozens of samples, though, you'll need to do your research up-front and the measurement just confirms your success. The below suggestions you should take as BROAD generalizations, you really need to look up each component of your system and pick ones that work together and give you what you need, all while minimizing power.
For your first critical decision (even if you put CPU as the #1 constraint), graphics. Do you just want desktop productivity with only the most basic 3d acceleration? Go for on-board Unichrome or (a bit older) Radeon Xpress (which tend to include the whole chipset, not just video). If you want some "real" 3d power for gaming, but don't rank that as the sole reason you own a PC, try to get one of the newer mobile GPUs. Personally, I went with a GeForce 6600, which draws low enough power to work in a passively-cooled config, but has enough horsepower to play previous-gen games at full res and highest quality (and most current games at the default quality). You might also consider driver support for it first - Many GPUs now offer a wide range of performance, dynamically selectable, so you can run in low performance (and thus low power) mode most of the time, then kick it up to play a game.
For the motherboard, if you don't need a ton of peripherals, uATX boards tend to consider power draw as a design constraint whereas most MBs seem to assume you'll just get a bigger power supply if necessary. And now we see that chipset makes a big difference as well - I'll apparently need to research this topic far more for my next build. ;-)
Which brings me to power supply... Most people don't think anything of it, and get the cheapest, biggest one they can find. I currently run all SeaSonic S-12s (well, one older SeaSonic, the model of which I forget but the same basic design as the S-12s). Nice quiet 12cm fan, and 85% efficient. They cost a little more, but keep your total power budget in mind - When I say I don't have a single system drawing over 100W at-the-wall, I mean it. I have one 380W in my file-server (spinning up four drives will most likely represent the biggest load your system sees), and the rest have 220W (the lowest SeaSonic makes), with not even a hint of instability. And don't neglect what a difference a few percent more efficient makes - On a high-end rig that draws 400W internally, going from 70 to 85% efficient will save a whopping 60W at-the-wall.
Currently, the biggest difference you can make comes from the CPU. Go with a P4, and you might as well abandon power consumption as a design constraint. On the opposite end of that spectrum, if you don't need a lot of horsepower, the Via Epia boards (of which you can now get a dual-CPU model, the DP-310) absolutely rock and have everything on-board - I run a passively cooled single-CPU Dual-NIC Epia as my internet gateway, with a CF drive, and the whole thing draws 26W (IIRC); yet, when necessary, I can use it as a low-end desktop machine fully capable of doing just about any common task short of gaming or video editing. For my "real" machines, I currently have Athlon64s (one RS400 chipset and one NForce4, the latter of which I now regret after reading the FP link). Though spec'd at a TDP of 65W, in practice they draw 30-35W under load, and 7-11W idle. A Pentium-M would give more bang-per-watt, but they cost a hell of a lot more. And as I mentioned, the next-gen Core Duos look very promising.
For memory, running one gig stick instead of two 512MB sticks (otherwise identical) draws only a bit more than half the power (and on the Athlon 64, two sticks frequently causes no end of headaches anyway). And of course, lower voltage means lower overall power consumption.
For HDDs, they all come out to the 15W ballpark. Ignore spin-up draw (except for picking a power supply, as I mentioned), and don't even bother telling them to ever spin down (under both Windows and Linux, in my experience, they never get to spin down for more than half a minute at a time anyway, which the spin-up surge all but makes up for). Basically pick what you like for HDD, it won't make much difference.
For displays, consider it a no-brainer to go with LCD. But a LOT of variation exists therein - You don't have much choice beyond trusting the manufacturer's specs, though. One area you can improve, however - If it has an external power brick, you can bet they used the cheapest crap they could find. Buy a $30 high-efficiency replacement with similar specs and you can drop the total by 25% easily.
Ummm... Nothing else comes to mind. Basically, you just have to do your homework, and decide what you actually need from your system - We'd all like a pair of SLI'd GF7800s in theory, but unless you do nothing but game, you might as well throw literally $20/month in the garbage for what the electricity to feed them costs.
How did you do it? Which components did you choose, and what tools are available to test things like power consumption and heat output?
Just a little meta-comment first... If you log in to post, you can have Slashdot tell you when someone replies. But since you asked, I'll presume you plan to check back in the near future. :)
For measurement, I use a simple kill-a-watt meter. WONDERFUL little toy, and pretty cheap. Unless you have access to dozens of samples, though, you'll need to do your research up-front and the measurement just confirms your success. The below suggestions you should take as BROAD generalizations, you really need to look up each component of your system and pick ones that work together and give you what you need, all while minimizing power.
For your first critical decision (even if you put CPU as the #1 constraint), graphics. Do you just want desktop productivity with only the most basic 3d acceleration? Go for on-board Unichrome or (a bit older) Radeon Xpress (which tend to include the whole chipset, not just video). If you want some "real" 3d power for gaming, but don't rank that as the sole reason you own a PC, try to get one of the newer mobile GPUs. Personally, I went with a GeForce 6600, which draws low enough power to work in a passively-cooled config, but has enough horsepower to play previous-gen games at full res and highest quality (and most current games at the default quality). You might also consider driver support for it first - Many GPUs now offer a wide range of performance, dynamically selectable, so you can run in low performance (and thus low power) mode most of the time, then kick it up to play a game.
For the motherboard, if you don't need a ton of peripherals, uATX boards tend to consider power draw as a design constraint whereas most MBs seem to assume you'll just get a bigger power supply if necessary. And now we see that chipset makes a big difference as well - I'll apparently need to research this topic far more for my next build. ;-)
Which brings me to power supply... Most people don't think anything of it, and get the cheapest, biggest one they can find. I currently run all SeaSonic S-12s (well, one older SeaSonic, the model of which I forget but the same basic design as the S-12s). Nice quiet 12cm fan, and 85% efficient. They cost a little more, but keep your total power budget in mind - When I say I don't have a single system drawing over 100W at-the-wall, I mean it. I have one 380W in my file-server (spinning up four drives will most likely represent the biggest load your system sees), and the rest have 220W (the lowest SeaSonic makes), with not even a hint of instability. And don't neglect what a difference a few percent more efficient makes - On a high-end rig that draws 400W internally, going from 70 to 85% efficient will save a whopping 60W at-the-wall.
Currently, the biggest difference you can make comes from the CPU. Go with a P4, and you might as well abandon power consumption as a design constraint. On the opposite end of that spectrum, if you don't need a lot of horsepower, the Via Epia boards (of which you can now get a dual-CPU model, the DP-310) absolutely rock and have everything on-board - I run a passively cooled single-CPU Dual-NIC Epia as my internet gateway, with a CF drive, and the whole thing draws 26W (IIRC); yet, when necessary, I can use it as a low-end desktop machine fully capable of doing just about any common task short of gaming or video editing. For my "real" machines, I currently have Athlon64s (one RS400 chipset and one NForce4, the latter of which I now regret after reading the FP link). Though spec'd at a TDP of 65W, in practice they draw 30-35W under load, and 7-11W idle. A Pentium-M would give more bang-per-watt, but they cost a hell of a lot more. And as I mentioned, the next-gen Core Duos look very promising.
For memory, running one gig stick instead of two 512MB sticks (otherwise identical) draws only a bit more than half the power (and on the Athlon 64, two sticks frequently causes no end of headaches anyway). And of course, lower voltage means lower overall power consumption.
For HDDs, they all come out to the 15W ballpark. Ignore spin-up draw (except for picking a power supply, as I mentioned), and don't even bother telling them to ever spin down (under both Windows and Linux, in my experience, they never get to spin down for more than half a minute at a time anyway, which the spin-up surge all but makes up for). Basically pick what you like for HDD, it won't make much difference.
For displays, consider it a no-brainer to go with LCD. But a LOT of variation exists therein - You don't have much choice beyond trusting the manufacturer's specs, though. One area you can improve, however - If it has an external power brick, you can bet they used the cheapest crap they could find. Buy a $30 high-efficiency replacement with similar specs and you can drop the total by 25% easily.
Ummm... Nothing else comes to mind. Basically, you just have to do your homework, and decide what you actually need from your system - We'd all like a pair of SLI'd GF7800s in theory, but unless you do nothing but game, you might as well throw literally $20/month in the garbage for what the electricity to feed them costs.
