Case fans fire but immediately quit spinning

When I power up all 6 case fans begin to spin but all immediately stop. No whinning no vibration its as if the power is just turned off to them. Also the fan on my mother board is not working at all doesnt even attempt to spin "not the processor fan" The processor fan works fine and so do the 2 onboard the video card. I noticed the problem while trying to play Doom3 a few days ago. The game would freeze for 5-10 seconds then begin playing again. More intense the action greater frequency of freezing. Also had some artifact "blue blocks". I have been told its most likely the power supply or the motherboard. How would I check to see which is the cause? Thanx in advance. P.S the system has been up and running for about 2 years in its current configuration, problem started about a few days ago.

Amd Athlon xp3200
chaintech ct-7njs mother board
Gig of ram
leadtek geforce4 4800 vid card
Lian Li full tower aluminum case
Enermax Whisper 431watt power supply