Random lock-ups, reboots?

[CFster]

Getting random lockups in drivng sims such as rFactor and GTR2. Nothing is overclocked but my video card. No artifacts present in-game. I can play for 10 minutes, or sometimes 2 hours then the screen will just freeze, the sound will loop 3 times then the system will reboot. Have tried with multiple drivers.

Coolbits detected optimal frequencies as 698/1544. Didn't want to push it so I backed down to 682/1504. Stock is 650/1320.

A64 X2 3800 Manchester
ASUS A8N-E, 1013 BIOS
(2X1GB) G.SKILL DDR400 F1-3200-PHU2-2GBZX
eVGA 7900 GTO 512MB, 92.91 drivers
Fortron AX450-PN

I can run SuperPI for each core over and over with no problems. Ran Memtest 86 for 2 hours - no problems. Runs 3DMark05 and 06 no problems.

Do you guys think this is a video problem? Can a card that is clocked to high manifest itself in this way (with no artifacts?). Temp never seems to go above 50C or so, but if it's getting hotter than that when it crashes I don't know, as it's cooled down by the time I reboot. Would core or memory speed be more likely?

 

[AristoV300]

It may be power supply issue, since you seem to have covered all the other issues. Overclocked GPU shouldn't cause reboots.

 

[CFster]

Any way to test that?

 

[AristoV300]

You should be able to use Asus Probe to see if your rails sag under load from the games. That should help you. Also check your components temps to see if anything is overheating.

 

[CFster]

+12V 11.90v
+5V 4.92v
+3.3V 3.26v
Vcore 1.36v

Just idling these are the voltage readings - slightly low. Is it something to be concerned about?