I've recently done some silencing/power reduction on a server i have at home, and i'd like some thaughts and advice.

The machine acts as a media file server, but doesnt so any transcoding, just shares out data with samba over ethernet.

Specs:

Pentium DualCore E5200
Asus P5KVM-AM motherboard
1GB DDR2
3x2TB SATA Drives
120mm rear exhaust fan

Last week i did some measurements and found the machine was drawing about 80w from the wall at idle. After some investigation, i decided to swap the noisey ancient bodged in PSU for a new 300w 80 Plus model from Be Quiet, which reduced the power consumption by 20w on its own. Removing an un-used TV Tuner and a second ethernet card saved me another 10w, so its now idling at 48-50w and a good bit quieter than before.

I'd have been happier with more like 40w, so i tried some experimentations with clock speeds, however the board doesnt give any options for undervolting, and i found that even clocking the CPU right back to 1ghz (6x166) didnt really make any noticable difference to the power draw (maybe 1w at best). I disconnected the CPU and Case fans temporarily and that seemed to save 2-3w, with the case fan seemingly being the bulk of that, but the drives were getting a little too hot for my liking with the reduced airflow so the fans had to stay.

So it seems i'm somewhat at the "end of the road" when it comes to tweaking the current hardware, and if i want any improvements i'm going to have to change things.

I'm guessing the three drives are probably drawing the best part of 15w at idle, meaning the mobo/cpu's probably drawing around 35.

What i'm wondering, is if there any any significant gains to be had from swapping the motherboard for one that DOES allow a degree of undervolting, or am i better looking at something newer? And even with something newer like a G6950 or celeron, am i likely to see any significant decrease in consumption, or is it going to end up being a big cash outlay for a 5w gain?

Basically, where would you go from here?

Cheers

If you want low power consumption, you need to replace that board and most likely the PSU. Asus doesn't usually do efficiency and "80 Plus" is useless when it comes to drawing <10% of the rated power.
While you're at it, you might as well replace everything. It doesn't have to be very expensive.

For a file server, you don't need a mainstream CPU. If you want to run 3 desktop drives, you will however need a PSU (there are great power-efficient boards which take DC but they can't run 3 desktop drives).
There are cheap Ontario boards out now which should be ideal for a file server. However if the only model you can source is the C60M1-I, an MSI or Intel board might be preferable.
Since Intel doesn't (so far as I know) ship Atom boards with 3 SATA ports, you can choose between an MSI Zacate (those are plentiful) or an Intel Ivy Bridge (Hxx, the others use more power). If you can find an affordable Ivy board and pair it with a G530, this might be your best option. There have been reports of very good power consumption numbers with Intel Ivys. The MSI Zacates are reportedly pretty efficent too but the CPUs aren't in the same league. Still, if you can get one cheap...

For the PSU, see picos or something like the least powerful Golden Green (check SPCR's reviews for other options). There are better PSUs but they're expensive.

Feel free to checkout my newer but rather similar build based on low power Ivy Bridge - http://www.silentpcreview.com/forums/viewtopic.php?f=28&t=65038. I got around 29W idle with older 80+ bronze PSU, 19W with HDDs off.

If you're worried about power consumption alone, replacing components is unlikely to pay off either financially or environmentally for decades. There's no point in big outlay for even (if you're lucky) a 20W difference. If however you're able to come across parts second hand, this may be worth considering both from an environmental and financial perspective.

You can use software to undervolt with some CPUs and motherboards. As you mentioned Samba I'm guessing this is Linux so you could take a look at Linux-PHC.

How is your RAM setup? If it's 2 sticks of RAM, try swapping for a single stick, it'll probably be about 2.5W each.

Also disconnect power and hard disk lights. It all helps!

Another step that might help with your existing hardware would be to go through the BIOS and disable everything that you don't need. It depends upon motherboard but there might be a small amount to be had there, more so if your motherboard has lots of off-chip controllers.

The biggest reduction in slectricity usage by a long way is of course to not have an always on system. Perhaps you should reassess whether you really need such a system and if you do, can you switch it off more of the time?

According to Anandtech's review http://www.anandtech.com/show/2339/21 this board draws a lot of power even when idle.

So replacing mainboard and cpu would be the way to reduce wattage even more.

As edh has pointed out, buying stuff brand new to save 20W doesn't make any sense, financially. Tinker with some undervolting, but my guess is it won't net you a big difference, if it was my system i'd leave it as is.

Thanks for that.

I guess its weighing up cost of the upgrades against potential savings.

As you say, theres little point spending £100 or more on hardware specifically to save power, if the savings going to take 10 years to balance out the expense.

My current 30w saving has likely dropped the annual cost to run it from around £85 to around £50, which neatly covers the expense of the PSU, and the machine is now pretty silent, which was the reasoning behind swapping the PSU in the first place. Obviously now the issue isnt so much "i need it to be cheaper to run" more, "how much lower can i get it without spending very much money"

I initially avoided atoms back when i built it, after reading a review/article by Toms Hardware, which showed a 45nm Core2 plus G31 chipset could more or less match the Atoms in idle power, but yet had a bit of grunt in reserve if it happened to be required.

I think if i were to change anything, i'd like to keep that requirement, meaning a desktop chip with a bit of grunt but that has very low idle power. I've been toying with the idea of using it as a MythBackend but nothing really concrete yet.

I've not found all that much info on how little power you can get away with on more modern systems. Toms seem to have revisited the orginal article using an i5-661 CPU, and managed to end up with 23w idle power from the wall, with a single 2.5" drive. I guess if we assume ~15w of my current draw is the hard disks which is fairly fixed and wont change, then the mobo/cpu etc is drawing around 35w. The clarkdale setup toms tested would presumably shave around 10w off my existing figure. I presume i might even manage a bit more still if i were to use a low end celeron or pentium chip.

As mentioned above, ivy bridge seems to take it a bit further, but at a large jump in cost, which i dont think would be worth it at this point.

I may be able to get my hands on a Pentium G6950 very cheap/free, however motherboards for them seem to have all but vanished from the market... Perhaps some suggestions on what boards would pair up with the G6950, and provide minimum energy consumption, plus a decent set of twiddles in the bios to allow me to undervolt the CPU etc? I may be able to find something suitable used, and i'm sure i can sell on the existing Core2 chip and mobo to reduce the overall cost of the swap?

Cheers

You shouldn't over-generalize because very different products get the same brand name and even (in this case) the same CPU architecture.
Atoms are unsuitable for your application (unlike AMD's equivalent) but the more efficient Atom solutions are very efficient indeed... and that was already true back in the day. It's just that the cheaper desktop Atoms are not supposed to be efficient, just very cheap.


Clarkdales go down to 15W, Sandys to 13W I guess and Ivys to about 10W. But most systems based on those boards burn a lot more. I'm talking Intel and MSI boards with few features, BIOS tweaks and/or minimal peripherals as well as extremely efficient PSUs.


Any basic Intel or MSI board with the least features (like the current Hxx chipsets).
It's not worth buying an obsolete board though (unless you can get it really cheap). Current gear is better and the cheapest current CPUs are really cheap (look up the G530, which isn't even one of the crippled models). The cheaper Ivy boards aren't that expensive actually but you can always get a Sandy. It would still be better than a Clarksdale.

Manual undervolting is over-rated. The lowest idle power consumption are typically achieved without manual undervolting. Undervolting is useful to lower power consumption at load however.

I've done the math... going from 40W idle to 20W idle would save me over $50 / year (PC on 24/7, electricity is expensive where I live at $.25 / kWh). So a 20W savings can pay for itself pretty quickly. I was looking at buying an Ivy Bridge setup that was around $200... pays off in less than 4 years. YMMV if you don't leave it on all the time or have cheaper electricity (I believe US national average is about half what I pay, grrr).