Robertsmalls' 23W (at idle) computer

[RobertSmalls]

Back in the day, I had an overclocked, overvolted Athlon PC with ten fans and two power supplies, because a single 300W PSU wasn't enough for my three hard drives. If I could figure out a way to put dual anything in that PC, I did it. Dual ethernet cards, dual optical drives, dual keyboards... there's room for it, so pile it in! Lots of enthusiast cases still have room for six expansion cards and four optical drives, so I'm sure today's kids are doing the same thing I was.

At some point, I got my hands on a proper CPU heatsink: the Scythe Ninja, pictured below. That's when I discovered that high-performance PCs can be very quiet. They also don't have to draw 300W.



My PC makes use of undervolted, low power components to minimize cooling requirements. I have an Athlon 64 X2 at 2.1GHz. Reducing the voltage from 1.4V to 1.1V reduced CPU power consumption by 62%, with absolutely no impact on performance or stability. I undervolt to the threshold of instability, then bump it up two notches, a procedure that is familiar to overclockers.

Given small power consumption and large heatsinks, I don't need any fans, and the PC has none. With a maximum power consumption well under 150W, I can get away with using another excellent, efficient piece of hardware: the PicoPSU. The PicoPSU is about 85% efficient at these very low power levels, while most PSUs are around 70% or worse. It's a piece of hardware that makes you wonder why it's not more popular.



I have a 30GB solid state drive, which makes the computer much more responsive-feeling, and has no moving parts and no noise. Unfortunately, SSDs have tiny capacity and large price tags, so I have a 0.5TB "internal" hard drive that I can plug in when I need to.

I bought a Radeon HD 5670 for its 10W idle power, but I don't need it to play Starcraft, so I'm running with onboard graphics for now. The mobo is a Biostar TA760G M2+, which is hard to beat in terms of idle power consumption.

Given my somewhat unconventional choice of power supply, need for good ventilation, and total lack of fans and optical drives, I couldn't find a case that suited the PC. So I took a sawzall and tinsnips to a very old case from the 1990's. I mounted it on the wall so visitors will know I'm a PC enthusiast.



You could build a PC like this for under $400. Or, if you don't need utterly silent and can settle for "virtually inaudible", then get a few good 12cm fans undervolted to 800RPM, a 5400RPM hard drive mounted on elastic cord, and a case that you can stash under or behind the desk.

At the least, if you know how to overclock, then you should undervolt your existing PC, and make sure the CPU enters lower power states at idle. Then check your temperatures, and think about running your fans off the 5V rail instead of the 12V rail if you'd like it to be a little quieter.

[Daox]

Awesome setup. I'm very impressed with the CPU undervolting power savings! I'm going to have to try that one out.

About two years ago I evaluated my old computer to try and make it more efficient. I too had it overclocked and was running things as fast as possible. My idle consumption was 170W at that point. With some reconfiguration and bringing clock speeds back down to stock speed I was able to get it to 141W, so it was still a mega power hog. Of course I couldn't even tell the difference in speed.

Shortly after Higgy and I both built new computers for ourselves. We have very similar setups as we conversed and built them together weighing each component. We did have some differences in components. I think he went with a faster Intel chip and I went with an Athlon X2 5050e (the "e" being their 45W chip vs the normal 65W). I also went with a large passive CPU heatsink. I did not spring for a SSD though, too expensive for me at the time. One thing I did go with is nVidia's hybrid SLI though. I REALLY wish they would have kept the technology around. It allows you to run onboard graphics card most of the time, and just turn on the 3d card when needed. I do occasionally game and also do 3d CAD work, so I wanted the nice 3d card. Other than that, I did suspend my hard drive with rubber bands. That made quite the noise difference and I'm very happy with the result. I was also able to pickup a 80 plus silver certified power supply for a good price. The result of all this is a 58W idle power consumption. I look forward to trying the undervolting though. I knew of it, I just didn't think it would have that drastic of an effect on power consumption.

My build: http://ecorenovator.org/forum/projec...-computer.html

[NiHaoMike]

Here's an old design I had for an efficient PC based on the Beagleboard:

The new Beagleboard has more USB ports and a built in Ethernet port.
BeagleBoard.org - hardware-xM

[RobertSmalls]

Processor power consumption (CPU, GPU, chipsets, maybe even RAM) is proportional to frequency times voltage squared. Hence a 29% reduction in voltage cuts power consumption in half. You can undervolt a 45W TDP Sempron to single-digit power consumption, which I think makes it a better choice than the Atom.

Your CPU ships at 1.15V, and I'm curious to know how much lower than my CPU's 1.10V it can go. Our CPUs are built on the same process, just binned differently.

Daox, you asked about my Molex-powered LED desk light. It's really simple. I cut a Molex passthrough off a 12V fan, and hooked it up to a switch and an automotive T10 socket. This socket is off a first-gen Honda Insight. You can get a T10 12V LED bulb for $3 on the internet. This one puts out double-digit lumens, but that's fine because that's all the more light I want on my desk at night.

If you want to get fancy, there are LED trailer lights.



Mike, that BeagleBoard is amazingly small. I'd be tempted to screw it to the back of that monitor and call it a laptop. :-P Battery operation would be a bit convoluted, though.

I bet you could get a nice Linux distro + complier on a 4GB microSD card, and have room for /home, too. I'm not familiar with the ARM processor. Can it handle things like YouTube and OpenOffice?

[NiHaoMike]

X86 is very inefficient compared to more modern architectures like ARM and Cell.
silentpcreview.com | View topic - beagleboard

Part of my job is developing embedded software for a custom board with a low power ARM7 microcontroller (clocked at 48 MHz), but we don't run an operating system at all. My understanding is that MHz for MHz, an ARM will generally beat an x86 because of all the legacy cruft in the x86 instruction set and architecture which use up gates in the CPU.

Ultra-mobile devices: Atom to beat ARM... just, says analyst ? reghardware Forums

Intel CPU's have a fast risc core and huge number of transistors to convert X86 instructrutions into risc instructions. ARM (and MIPS) are risc cores, so the do not need to waste transistors and power converting a legacy instruction set into something that can be decoded efficiently.

Intel and Via CPU's use power to get data to and from the north bridge. The north bridge uses power to get data to and from the memory. ARM (and MIPS) CPU's have a memory controller built in like AMD CPU's, so it only takes half the power to get data from memory to the CPU compared to an Intel or Via chipset.

These two advantages more than make up for the better manufacturing processes that Intel uses for Atoms. ARM (and MIPS) give better performance per watt than X86.

In other words, "You see, there's Allie Moore (TI OMAP 4), Tiffany Yep (Nvidia Tegra 2), and Jean Ma (Intel Atom) in this room. Given that Jean Ma is aging, ugly, and obese, it would be foolish for me to fall in love with her when the two others are both young, beautiful, and slim. Yet that's exactly what the PC industry did."

[tasdbois]

I use a rather old athlon 64 laptop with an external 19 inches LCD monitor at low brightness. The whole setup uses 35 watts during normal use.

[NeilBlanchard]

I have an original Ninja sitting here on my desk. Matt, have you seen the site Silent PC Review?

silentpcreview.com | Everything about Silent / Quiet Computers

It's all about quiet computers and low power consumption is a big part of that. (I'm a moderator on SPCR.)

[RobertSmalls]

Yes, I used to be an avid reader of SPCR and occasional forum participant. When I signed up on EcoModder, I recognized your name from SPCR.

Unfortunately (or not), I've "solved" the issue of silent computing with elastic HDD suspension, good heatsinks, and large, slow fans. Or, better, no moving parts at all. There's not much left to read about, or post about, at SPCR.

[Clev]

Originally Posted by tasdbois

I use a rather old athlon 64 laptop with an external 19 inches LCD monitor at low brightness. The whole setup uses 35 watts during normal use.

Agreed. I replaced my 24x7 "server" desktop with a Dell C640 laptop with a broken screen, which draws about 12-13 watts at idle with the hard drive spun down. My daily use machine is a dual-core Toshiba laptop that pulls 30-40 watts at full tilt. My "power desktop" was finally unplugged and stuffed in the basement when I realized I hadn't turned it on in 6 months.

I've considered moving the "server" to a Sheevaplug or similar ARM machine to shave off a few more watts, but I haven't had a chance to investigate the availability of mplayer, sox and other software I need on the ARM platform.