My colleague is using a Fujitsu Esprimo E900 (VFY:E0900PXG11NL) desktop PC that revs its fan every couple of minutes when a CPU core hits 70 degrees Celsius according to SpeedFan 4.51. Enabling "Automatic fan control" in SpeedFan doesn't help much (Is it still learning? Does not being able to show fan speeds affect it?).
The CPU is almost idle and there's no apparent dust in the case and another colleague says it's always revved. Is there a BIOS setting to control the fan speed?
Room temp is 25 C and desktop is clear. HDD temp is 40 C and average idle core temp is 60 C.
It appears that the fan can be controlled:
Silent Fan - Independent temperature related processor fan and system fan supervision and control
System Guard - View and adjust Silent Fan features
Enhanced mode makes the front fan rattle (otherwise it would be the answer),
Silent mode doesn't help, and
Disabled makes it sound like a vacuum cleaner. I could ask the hardware guy about the thermal paste but all stock paste i've used lasted much longer than this and it seems all fans are entirely off until needed.
My colleague is fine with the revving on
Auto, so i can't test SpeedFan again while BIOS fan control is disabled.