It was built to replace a computer used as a workstation and server (for Slim Devices SlimServer, web server, FTP server, SSH server, etc.). Acoustically, I was almost totally happy with it (Coolermaster case with AcoustiPack Deluxe + 2 exhaust Panaflos @ 7V with EAR grommets, passive northbridge, Athlon 1700+ with Thermalright SLK-800 + Panaflo @ 7V, 300GB Maxtor DiamiondMax 10 with AAM + NoVibes & Seasonic S12-430) but it was too slow for some tasks (encoding, etc.) and poor at multitasking (disk I/O would interfere with SlimServer, for example). This computer is now just a server (CPU undervolted + Panaflo @ 5V, case exhaust vents blocked and just PSU as exhaust).
The new computer needs to do everything from audio/video encoding to minor gaming and still be fairly quiet. Whilst not going over the top (top-of-the range CPU, for example) there's enough there to make it fast for my needs (the X2 CPU and Raptor HDD come to mind). The spec:
Case - Antec P180, silver
Case fans - 2 x Nexus Real Silent 120mm (with Acousti Products AFM02B Ultra-Soft Fan Mounts)
PSU - Antec Phantom 350W
Motherboard - ASUS A8N-Sli Premium
CPU - AMD Athlon 64 X2 3800+, E4/Manchester
Heatsink - Thermalright SI-120
Heatsink fan - Nexus Real Silent 120mm, orange
RAM - 2 x 1 GB Crucial PC3200 (CT2KIT12864Z40B)
GPU - ASUS N6600GT Silencer/HTD/256M
Sound card - Creative X-Fi Platinum
HDD 1 - Western Digital Raptor 150GB (WD1500ADFD)
HDD 2 - Samsung SpinPoint P120 250GB SATA (SP2504C), Nidec motor
Optical - NEC DVD-RW (from old computer)
I wanted to keep the thermal management simple and didn’t mind if it was a little noisier than the old computer as it’s not on all the time. Different arrangements of fans weren't tried. The top exhaust fan was removed and sealed with aluminium foil tape. The PCI vents were also sealed with tape. The rear exhaust and PSU duct fans were soft mounted. The top section HDD cage was removed (as the hard drives are in the PSU chamber) along with the front dust filter and slatted doors.
The first configuration was with the PSU fan and rear fans at about 5V. Even with the CPU fan at 12V the computer would crash after 5 minutes of RTHDRIBL. Increasing the rear fan speed to more like 8V kept it stable. At 8V it remained stable when the CPU was run at less than 12V. The impression I got was that either the video card heatsink arm (positioned over the CPU heat sink) gets a lot of cooling from cross-flow from the rear fan, or that some other part of the video card (maybe RAM) is the limiting factor.
The noise with the fans at 8-10V is too much for me, so I used the motherboard QFan feature to idle at 7V. All three fans are connected to the motherboard CPU_FAN header (via 2 3-pin splitters daisy chained with the tacho wire removed except for the lead to the CPU fan) and QFan enabled with a target temperature of 60C. This relies on GPU-intensive programs also using the CPU, thus allowing QFan to increase the rear fan in line with the CPU fan. It works for every program I've tried.
Moving the CPU fan towards the front of the case lowered GPU & CPU temperature at the slight expense of motherboard temperatures (by about 1 or 2C, so might not be significant). My reasoning was that that the faster moving edge of the fan is in line with more of the video card heatsink and CPU heatsink heatpipes. Removing the front dust filter and slatted doors made more of a difference (2 - 3C for CPU and GPU).
Temperature-wise, the final result (with an ambient of 21C) was:
Idle:
Fans - 667rpm
CPU - 38C
Motherboard - 40C
GPU - 53C
WD Raptor - 36C
Samsung SpinPoint - 29C
2 x CPUBurn:
Fans - 981rpm
CPU - 59C
Motherboard - 40C
GPU - 51C
WD Raptor - 33C
Samsung SpinPoint - 27C
RTHDRIBL:
Fans - 879rpm
CPU - 51C
Motherboard - 40C
GPU - 68C
WD Raptor - 33C
Samsung SpinPoint - 27C
The CPUBurn temperature at 21C ambient is a little high. I wanted to allow for a (freak!) UK ambient of 30C. Adding 9C to the CPUBurn temperature would make the CPU 68C (more the 65C AMD maximum). Setting the fans to 12V (QFan disabled) gave:
2 x CPUBurn:
Fans - 1148rpm
CPU - 55C
Motherboard - 39C
GPU - 50C
WD Raptor - 33C
Samsung SpinPoint - 26C
At 30C ambient and fans at 12V, the CPU would be at 64C – only just below the maximum. I’m not sure what S939 motherboards use – a socket thermal sensor or one on the CPU die. Nor do I know whether Asus boards give an offset reading(I read some where that they always add 10C). Interestingly, opening the front door gave:
2 x CPUBurn:
Fans - 1148rpm
CPU - 52C
Motherboard - 39C
GPU - 45C
WD Raptor - 31C
Samsung SpinPoint - 25C
Perhaps removing some of the vents along both sides of the front door might help but still block sound. The chances of having an ambient of 30C and using 2xCPUBurn are slight (hopefully I’d be outside and computer off) but it can just handle it with the door closed and has 4C safety margin with the door open. It’ll do for me.
Thanks to the QFan, the acoustics are better than I was anticipating. The Raptor and Samsung seeks (AAM disabled on Samsung since it doesn’t do much) are louder than I was expecting but quiet enough to provide some feedback without being annoying (but, for me, not quiet enough to be in a server like the Maxtor is).
Despite that, I like it more than the server since the Nexus fans @ 7V are quiet and smooth, whereas the S12-430 PSU has an annoying click (but very quiet overall). I might replace the S12-430 with an Antec NeoHE 430W to try and get that same smooth sound.
Anyway, thanks to SPCR and the members of the forum.
Some pictures (linked to full-sized ones):
Overall view.
Clearance on the lower side of the video card.
Closer view of the video card.
There's more room available between the heatsink and fan if the video card is angled before being screwed in.
Edit: Removed older picture of before re-doing cabling