I recently completed my new computer and I am happy to report that it is very
quiet. It isn't silent, but it's close and much, much quieter than my last computer. It's roughly based on Ralf Hutter's system as you'll see. First, some specs:
Asus P4C800-E Deluxe
Pentium 4 3.0Ghz w/ HT
1GB Corsair XMS PC3200-LL RAM (2x512MB)
160GB Hitachi HDS722516VLSA80 SATA Hard Drive
ATi Radeon 9800 Pro 128MB
Turtle Beach Santa Cruz
Lite-On 16x DVD-ROM Drive
Pioneer DVR-106 DVD+/-RW
Logitech Z-560 4.1 Speakers
Zalman CNPS-7000A-AlCu HSF @ 5V
Evercool 120mm Aluminum exhaust fan @ 5V
Panaflo 92mm L1A intake fan @ 5V
Arctic Cooling VGA Silencer on low setting
Antec SL350S Power Supply
With all fans running at 12V and the VGA Silencer on high while idle the CPU runs at 27C and the ambient case temp was 30C. After leaving CPUBurn and Prime95 running overnight, the CPU was at 44C and the ambient temperature was at 31C.
With the fans at 5V and the VGA Silencer on low, the CPU idles at 30C with an ambient temperature of 30C. After leaving CPUBurn and Prime95 on overnight, the CPU was at 52C and the ambient temperature was 31C.
I didn't have E.A.R. isolators to mount the fans so I used some #6-32 nuts and bolts from the local Home Depot with rubber washers between the fans and case. It seemed to have worked really well.
Subjectively the machine is very quiet as I said, but not silent. The loudest component in the system is the PSU, which I may look into down the road. The VGA silencer and both fans are completely inaudible.
Also, I want to point out that I am amazed with this hard drive. Even while grinding away I cannot hear it over the PSU. It is an extremely quiet drive and I think the rubber mounts on the BQE help.
I'm very pleased with how this project turned out
I know that the CPU while idle with all fans at 12V is lower
than the cases ambient temperature which is not physically possible in this type of cooling setup. However, what I am giving as the ambient temperature is the "MB Temperature" which I believe is the temperature of the northbridge. It should be a rough estimate of the ambient temperature (which should be a few degrees C lower), but it really isn't.