Building a quiet and energy efficient PC has been on my To-Do list for some time. Since we needed a new family computer and I was in dire need of a new “project” I gave it a try. Our requirements were:

• Not audible under normal noise levels
• Not more than 50-60 W power consumption on idle
• Fast enough for web surfing, office work and video playback
• Doesn’t need to support modern games (got my PS3/Xbox360 for that)
• Not more than 450 Euro

This is going to take some work ...

These are the components I choose:

• CPU: Athlon X2 5050e – a 2.6 GHz dual core processor which will step down to 1 GHz on idle load (58 EUR)
• Mainboard: Asus M3A78-EM (75 EUR) – it has 12 USB ports, HDMI, DVI, DisplayPort, Gigabit LAN, 8 channel HD audio and a fast on-board GPU. This mainboard has a AMD 780G chipset with an integrated GPU which is DirectX 10 compatible and supports hardware based decoding of different HD video algorithms. That’s all you’ll ever need if you don’t want to play the latest 3D games. Leaving out an external graphics card reduces power consumption and heat by a large margin.
• RAM: 4 GB DDR2-800 (52 EUR)
• CPU cooler: Ninja Mini – can be used to cool the 5050e passively (35 EUR)
• HD: Western Digital 640 GB (54 EUR) + Sharkoon HDD Vibe-Fixer (10 EUR)
• DVD burner: Pioneer DVR-216 DVD (29 EUR)
• Power supply: Enermax PRO82+ 385W (60 EUR)
• Case: Sharkoon Rebel9 (55 EUR) +  120mm Arctic Cooling PWM case fans (5 EUR)

Total price was about 433 EUR + shipping.

The mainboard's back panel - including HDMI, DisplayPort and external SATA.

It has been years since I last put together a computer, so I had the chance to make a number of mistakes. Here are some of my learnings during this project:

• Modern mainboards have 2 power connectors, don’t forget to connect the second, smaller 12V plug
• Don’t use too much thermal paste. On my first try I used the paste which came with the Ninja Mini and spread more than the recommended rice-corn-size drop. I ended up with an idle CPU temperature of 45 degrees, which I thought was way too high. I took everything apart again, cleaned up the mess and applyed the proper amount. Now the CPU temperature was at 36 degrees, almost 10 degrees less.
• The AM2 socket version of the Ninja  Mini metal clamps can be adjusted. If they don’t fit without you almost breaking the mainboard, try to loosen them up a bit (even if you have to bend them).
• The power supply fan was supposed to be quiet. Once I had everything up and running I noticed a slight grinding noise. The fan’s bearing seemed to be out-of-balance. I took apart the power supply and used a second 120mm case fan for it.
• The Asus mainboard has only one PWM enabled, controllable fan connector (for the CPU). Since now I had to hook up the power supply fan as well (the internal connector couldn’t be reused because it’s not a standard fan connector) I was happy to see that you can chain the Arctic Cooling fans. You connect the first one to the mainboard’s CPU fan connector, then the second fan to the first one. Once you’re done the BIOS can control all fans at once, keeping them at the same speed depending on the CPU’s temperature.
• If you want a quiet computer, use components that emit as little heat as possible. Then you need to get rid of everything which can cause vibrations. Separate the hard drive and all fans from the case using rubber rails/plugs.

Only 2 fans, the PSU fan has been replaced and I added rubber pins to reduce vibrations.

All in all, there’s just one rule of PC building:

If it doesn’t fit, don’t force it. You’re probably doing it the wrong way.

Done! The CPU is cooled by heatsink only.

So, now that everything works, how is it?

• During the day I can’t hear the PC running unless I put my ear on it, when it’s very quite I hear the noise caused be the air flowing out of the case
• The 780G on-board graphic is fast enough to play 1080p HD video and to decode it under very little CPU load
• Power consumption is similar to a laptop (50-60W on idle, 80W under load)
• The CPU’s temperature is at 38 degrees Celsius most of the time, goes up to 55 under heavy load. The fans rotate at a slow 500-600 RPM 90% of the time.
• I put the Windows 7 RC on it, which by the way, rocks

Harddrive mounted with the Sharkoon HDD Vibe-Fixer.