Comment 47 for bug 380303

Once again then ... if it helps anyone..
On my x200s, this problem is definitely related to the wifi adapter.
1) Everything can be idling ever so nicely after bootup, but when you stress the CPU a bit, the fan ramps up and does not come down to level 0 - in spite of CPU going back to idle temperature. Waiting an hour does not help.
2) The fan hysteresis seems to be influenced by the mini-pcie wifi adapter. Disabling the adapter results in a drop in reported mini-pci temperature, and after a bit of cooling, the fan throttles back. Yay, though obviously it's annoying to turn off your wireless every time you want the fan to quiet down.
3) The problem seems to be solved by setting power management on through iwconfig. On the x200s, this drops the reported mini-pci temps by 6-7 degrees, and appears to let the fan throttle back along with the CPU temp. Been punishing the laptop for half a day here, and it seems to work perfectly now.