I have heard a lot of reports about the fan not working correctly out of the box under Ubuntu with my machine (ThinkPad X220), but I've always noticed that it cranks up under heavy load and slows down when idle (seems normal to me).
For fun, I installed lm-sensors to compare fan speed with CPU temperature. lm-sensors lists 86 C as "high" and 100 C as "critical" temperature for my CPU. I notice that under extended, 100% CPU load, my fan cranks up JUST enough to keep the CPU exactly at 86 C, and at idle, it slows down to keep it right around 55 C.
Does this sound like good behavior to any experts out there? Is it dangerous for my CPU to be at 86 C for extended periods? How long is that okay? Thanks!