I have an overheating issue on my netbook (ASUS EeePC 1015PW), which I'm trying to troubleshoot. Using lm-sensors while overheating gave me this output : acpitz-virtual-0 Adapter: Virtual device temp1: +86.0°C (crit = +100.0°C) eeepc-isa-0000 Adapter: ISA adapter fan1: 4089 RPM coretemp-isa-0000 Adapter: ISA adapter Core 0: +82.0°C (crit = +100.0°C) Core 1: +80.0°C (crit = +100.0°C) But I can't hear the fan. So I enabled manual pwm controling and set the fan to full speed, and after a few minutes I got this output : acpitz-virtual-0 Adapter: Virtual device temp1: +65.0°C (crit = +100.0°C) eeepc-isa-0000 Adapter: ISA adapter fan1: 4016 RPM coretemp-isa-0000 Adapter: ISA adapter Core 0: +62.0°C (crit = +100.0°C) Core 1: +58.0°C (crit = +100.0°C) And this time I could hear the fan spinning. So there's quite obviously an issue with either fan control or fan monitoring. Hence the question : what kind of physical information does the fan sensor really report? Thank you PS. I should have added that the computer is a small, hard-to-disassemble netbook, so I can't and don't want to try experiments like "block the fan and see what the sensor reports".