Laptop fan only spins if there's no operating system to read. Fan works fine while trying to PXE.

I have a laptop whose fan only spins if it's not reading from a disk on boot. As soon as it starts to read gparted from a cd or windows on the hdd, no fan. If i make sure it's free of operating systems, it's fine. Goes into PXE boot, fan still spins. No PXE server since it's my home network, but it does look for one and the fan keeps spinning. Thoughts? This is driving me nuts.

edit: Okay, I'm an idiot. All I had to do was wait 30 seconds and realize that the fan only kicked off while the BIOS was "handing off" fan control to the OS ACPI. Even when I booted to DOS, the fan picked back up, so I'm assuming that was the BIOS realizing that DOS wasn't doing the job and took control back.

I got it from my brother when he got a new one because of the issues I'm trying to fix. My dad had looked at it and said the fan wasn't spinning and that I would probably need to get a new one for it. I took it for granted that he was correct and I've now wasted hours trying to troubleshoot a problem that never existed.

The overheating issues are still real, though. Guess it's time to start scraping thermal paste.