Fedora: controlling the power supply fan

[YarrOfDoom]

The fan of the power supply is very noisy, because it always runs at full speed. I'd like to have it controlled in function of the current temperature, but fanspeed isn't detected.
Running sensors returns (beside the voltages) 2 temperatures and 2 fanspeeds. One of those fanspeeds is always 0. There are indeed only 2 fans (CPU and power supply) in the computer, and the one that gets displayed correctly is the CPU fan.

Does anyone know why the second fanspeed isn't detected, how to solve that, and how to get that fan under control?

Thanks

edit: I'm running Fedora10 and the output of ls /proc/acpi/fan/* was that it couldn't find the file/directory.

[ashitpro]

Can we really have control over SMPS fan?
According to my knowledge, we can only control the CPU fan...
That's what ACPI does in Fedora

Regards,
Ash

[Banfa]

The second fan you are getting a zero speed for is the case fan (which you haven't got installed). Most modern motherboards have an option for a case fan and so do most cases, often a 120mm fan which can shift the same amount of air as a standard 70mm fan at a much lower speed (and therefore less noisily). Some "gaming" cases come with a fan (or a place for one) that is the full width of the case ~240mm.

I think you can get PSUs with fans that are controllable (or at least have their own control) but that is on a high end PSU rather than the sort of bog standard PSU that you get in a case.

As an aside I recently saw a new CPU cooling fan design with 9 rather than the standard 7 blades and with notches in the blades. The nine blades meant it could run a little slower to shift the same amount of air and the notches break up the vortexes at the trailing edge of the fan blade where the high-density and low density air recombines. It's the vortexes that create the noise so lower speed and smaller vortexes makes the fan a lot quieter.

[YarrOfDoom]

So the only way to get it quiet is to get it out (<- bad idea).
Thanks for explaining though.

[Banfa]

The is another way, first put on some wellie boots, then find the big thick lead that runs from the mains outlet to you PC and using a pair of leads cut it.

You should then find your computer makes almost no noise at all :D