Building a Silent Computer

Having built a quiet computer for Camilla, my next goal was to build a really quiet one for myself. It was going to sit on my desk, maybe half a metre from me, and was across the hall from the bedroom, on the route for the through-breeze we want in summer...

Components and Planning

The internals were the same as Camilla's computer — Asus P5Q-VM motherboard, Intel E8400 Core 2 Duo cpu, Thermalright HR-01-PLUS heatsink, Corsair 4GB (2x2GB) PC-6400 800Mz memory, and Western Digital WD10EADS 1TB 32MB + Samsung HD103UJ 1TB 32MB disks — but in an Antec NSK 3480 case with EA 380 watt power supply. All the components were sourced from IJK, except for the case which came from I-tech.

Building

The NSK 3480 case is not as solid as the Mini P180 and constrained by its size. Careful routing enabled me to keep the cables out of the way, so as not to restrict airflow.

A minor annoyance is that the fan speed switch for the 120mm Tricool case fan has nowhere to go - on the Mini P180 both fan switches have slots in the back of the case. Also, I never managed to get the sides and top back on perfectly (perhaps because I switched the sides around to stop noise coming through the CPU vent) and the side with the vent seems to vibrate, so I left it off.

The power supply was a real nuisance. It has way too many cables, which have to be parked somewhere. And the SATA power cables had the first connector maybe 5cm from the power supply, just too short to reach either the hard drive or the DVD drive nearby. These cables were obviously designed for this case, but with the power supply the other way around. As a result of this I had to use even more cabling - the molex to SATA converter - to get power to the top drives.

It's very cramped in the top compartment. I thought the drive here would have cooling problems, so I put the Samsung drive here - experience with the earlier computer suggests that runs a little cooler than the Western Digital drive. But it turns out that the bottom drive runs hotter.

Despite using the identical heatsink and motherboard/cpu as with Camilla's computer, the heatsink didn't screw down as tightly — I didn't need to use the wrench with the tightening screws, and they went as far as they physically could without a real sense of resistance.

I went into the BIOS and made the obvious changes: removed the floppy, changed USB to "full speed" instead of "hi speed", set the SATA controller to AHCI, enabled ACPI 2.0, set the CPU fan to None to stop it complaining on boot about it being missing.

Performance and Noise

When idling at a room temperature of 18, the CPU is about 25 degrees and the system at 38. Under full CPU load - running two burnP6 processes for ten minutes - the CPU temperature rises to 42.5. These figures are all about 7 degrees warmer than on Camilla's computer, which I fear is because of the heatsink mounting but could be because I have one fan less or because the motherboard is just calibrated differently.

The stock system is way quieter than my old computer, but sitting on my desk instead of on the floor was still clearly audible.

Improvements

1. I swapped out the power supply for an Antec Neo HE 430. Unfortunately I didn't realise that, while modular, this is bigger than the Earthwatts unit! To get the cabling to work at all I had to move the hard drive out of the top compartment and mount it upside down at the top of the bottom compartment (screwed through the rubber grommets from above).

This improved the noise to the point where it's unclear whether the system noise is dominated by the power supply, the 120mm TriCool case fan, or the hard drives.

2. I turned AAM on on the two hard drives, using hdparm. This has clearly reduced the seek noises, taking the "edge" off them, but may not have affected the idle noise.

?. I plan to replace the Antec Tricool fan with a 700rpm Noctua SF-12B ULN, and run a duct to that directly from the CPU heatsink.

?. I could use an SSD for the system software and /home, leaving the mirrored 1TB drives for rarely accessed images, music, etc. But unless the drives park their heads after a period idle, that will only help with seek noise, not idle noise.