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14 May 2010  

Windows 7 x64
Strange fan behavior


Why is the fan (only one fan in this crappy HP pavilion dv6835eo notebook) running at almost max rpm for at least five minutes during and after logon, but not otherwise? If i check the temps with HWMonitor 64 they are low, that is, under 40 degrees celcius so the fan should not be running as much as it is.

When i power on the comp, fan spins up to max for a few secs (normal behavior) then run at very low rpm during the whole boot process until i get to the logon screen where it freaks out and start to get noisy. As i said, it stays that way for at least five minutes despite low temps. Same thing when waking up from sleep mode and hibernation. Using latest F.32 bios. Trying to rollback but can get hold of older version.

Its a fresh Win 7 x64 install with latest drivers. CPU and GPU throttling working. No aparent CPU-hogging software in the background or anything like that. CPU usage is less than 5%.

It feels like Windows 7 is ignoring the laptops own fan speed control for five minutes or so.

Aside from this issue, fan control, power schemes and everything else is working good.

I've been playing around with DSDT extracted from the registry (and then put back with ASL compiler etc etc) to try to change temp thresholds and stuff like that but it wont help a bit. No change whatsoever. Been looking at this guide How to Reduce Fan Noise on HP Notebooks: Patching the DSDT table to do it. My DSDT table and its fan/temp section is unfortunately a bit more complicated than in that guide.

Also tried at least ten different fan speed monitoring software including SpeedFan and whatnot, but none of them are able to detect my fan and its RPM.

Any suggestions?
My System SpecsSystem Spec