I have an HP ProBook 6450b laptop which runs Ubuntu 12.10 and Windows 7. It had a tedious and potentially expensive problem: when running Linux, the CPU fan would fail to turn on until the CPU temperature reached 105℃. This was dangerously hot. I wrote about the problem in detail on the Ubuntu Forum, including links to my conversations on the
linux-acpi kernel list.
After spending about a month trying to find a software fix for this problem, I decided it was time to get the soldering iron out to fix the problem. Here's what I did: