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[CPU/fan speed] Why do my chassi and CPU fans go crazy immediately? (piefed.blahaj.zone)
submitted 3 weeks ago by to c/techsupport@lemmy.world
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I have fine tuned my fan curves in the BIOS and normally, even when I used to game, the fans wouldn't speed up unless there was actual heat to dissipate. Now, I'm digitizing analog tapes using ffmpeg on Linux with the encoder h.246. This smart little thing auto detects the number of CPU cores available - 18 in my case - and uses them all. As soon as I hit ENTER ("start" or the likes for Windows users), my fans blast at full speed. Not that I'm trying to determine CPU temps by hand feel, but the air coming out of the chassi doesn't feel hot at all - at least compared to when I used to game, but maybe that was more the heat from the GPU? Even so, how could the CPU heat up to temps requiring maximum fan speed in an instant? Or is it so that the fans (or their controller or the likes) anticipate high temps and spin up preemptively?

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[–] 1 point 3 weeks ago

Hysteresis. Make sure your fan control software offers this. A lot of fan control software is dogshit/designed for older CPUs that didn’t heat up so quickly. You want hyateresis to even out the spikes. It’s essentially a delay in ramping up your fans.

I set my ramp up to be reletively quick, but ramp down to be a lot slower. I think 1 second ramp up, 2 seconds ramp down in my bios. If I had the choice it’d be 2 second ramp up and like 5 seconds for the ramp down.

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