I've got a Dell Optiplex GX280 mid-tower form factor that suffered a CPU fan failure and shut itself down. I've replaced the fan with an OEM equivalent Delta fan with the 5-pin configuration required and it still has problems booting.
Safe Mode boots fine, operates normally for any length of time, and shuts down normally.
Normal mode gets as far as the Windows XP logo and after 2-3 seconds it does one of two things:
If the BIOS maintenance log has been cleared of thermal events, the fan goes to max speed and it sounds like a jet on takeoff.
If the BIOS events are not cleared, the unit powers down.
I'm concerned that either the CPU temp sensor is now faulty, the motherboard sensor is faulty, or there's a driver loading at startup that's stuck thinking the CPU is overheating.
Does anyone have any suggestions on what may be causing this and how to rectify the issue?