system shutting off

[jaylee]

My 1gig thunderbird and fic az11e with a 300w supply are losing power and wont power back up for about 15 min. Everything feels cool and my temp gauges are low. If i use a friends 250 supply it powers up fine. do i have a bad supply, bad mb or an incompatibility problem. I may run fine for 5 hours or 5 min.