Joined: 04 May 2005 Posts: 12587 Location: Arizona USA
Posted: Mon 24 Apr 2006, 00:10 Post subject:
Solution for noisy case fan
I recently bought an Aspire X-Qpack case. The case fan was unacceptably loud so I used a trick that worked to quiet an older H-P computer that also had a fan that made a lot of noise: I replaced the 12 Volt case fan with a 24 Volt fan that I bought from Digi-Key.
(The original case fan was installed backwards too; it sucked the warmer air out of the case instead of blowing cooler outside air in. Fan bearings don't last as long that way because of the higher air temperature. Believe it or don't, a few degrees makes an appreciable difference in bearing lifetime.)
The 24 volt fan was still unacceptably loud at 12 Volts, so I put a 7808 regulator in-line to drop the voltage to 8 Volts and now it can't be heard over the noise of the CPU cooling fan that came with the 2800+ Sempron CPU. It probably doesn't move as much air at 8 Volts as the original case fan did at 12 Volts but I think it will be enough to cool the components I put in the computer.
The Aspire case comes with two thermal sensors of a thin tab shape for inserting between surfaces. They connect to a temperature display on the front of the case. One of the sensors is labeled CPU and the other HDD, but they can be located anywhere in the case.
None of those solutions address the fundamental issues of case venting and cooling. As I've said before, all fans need dismantling and lubricating with MoS2 grease. If noise is a problem choose a sleeve bearing rather than balls and smear MoS2 grease on the shaft as an assembly compound before reassembling. Although case fans should never be necessary, they should, where fitted, be mounted to exhaust hot air regardless of lower implied lifetime - removing hot air is what they do! A case fan should never be fitted lower case front (cf. AMD document).
Attention to airflow from a better component disposition is the first essential to correct aerodynamics. Replacing the single necessary fan in the PSU with an hi-flow professional unit with a properly lubricated sleeve bearing is then more than sufficient; I use a Papst unit.
Anyone experiencing overheating or fan noise should heed the above and hot-foot it off to their local library for books on fluid flow and aerodynamics. Don't expect any help from the computer trade - they are complete ignorami. I offer you BTX - QED.
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