Computer shuts down after a few minutes

[bike fixin guy]

I just did a rebuild on my PC, new mother board (Asus M2R32-MVP) ATI Athlon 64 X2, ATI Sapphire 3650 512 DDR PCI-e. I re-used my Maxtor 250 gig harddrive (ide), and DDR ram one 2gig stick new, one older 512 stick (not sure of speed on either) Case and 450 watt ps

When we first started it up it ran fine loaded up XP, drivers and other software with no problems. Only ran a couple of songs on media player called it good. Started the pc later and it will only run for a couple of minutes and then shuts down. It will start up again if I let it sit but shuts off again in the same length of time. I can feel no sugnificant heat in the case or smell any electrical burning. Any suggestions?

[MaDef]

That's a classic sign of overheating.
Did you apply thermal grease between the cpu and heatsink when you swapped everything?

[Ikon]

Yeah turn on the PC and go into the BIOS, go under hardware monitor and check the temperature of your CPU. Let it run for 10 minutes maybe if it will get there and check the temperature, make sure it is not running to hot.

[bike fixin guy]

yes we applied the thermal grease to the cpu. I am thinking it may be th board because it does the same thing out side of the case too.

[strollin]

Is it possible you used too much thermal grease? It should be just a thin, even layer. More than that could hinder heat transfer from the CPU and the heatsink.

[MaDef]

After rereading your post, I wonder if your powersupply might be a bit small or might be on it's way out.