I ran into a similar issue but it turned out to be a bum motherboard. It seemed a shame to change the motherboard due to a power issue on a fan connection so I used an adapter I had to run the fan from a connection from the main power supply but ran the tachometer wire to the old connection so the fan speed could still be monitored. Not a hard thing to do but in this case it saved my friend from buying a new board.
This is about to drive me crazy. After anywhere from one to two hours the CPU fan will just stop. I've checked the obvious, and gone into the BIOS, unchecked the Smart Fan option and set the fan to run at high speed continuously.
Does anyone know how to check a CPU cooling fan outside the case? Or know of an inexpensive and good CPU water cooler?
Gigabyte GA-965P-S3 mobo, Award Bios 7.0
Intel 630HT 3.0Ghz CPU with stock heatsink and fan, not overclocked
Antec SP500 PSU
Maxtor 200Gb SATA HDD
1.5GB Corsair PC-5300 Ram
Memorex 16X Dual Layer DVD burner
Memorex 52X CD-RW
Windows XP SP-2