Computer powers off when playing games, will not come back

I'm frustrated!

I just got a new motherboard (ASUS M3N72D) and a 2nd Graphics Card to do SLI with. The computer runs great, but when in Microsoft Flight Simulator 2004 or Flight Simulator X, the computer will just turn off completely as if someone pulled the power cord out of the back.

When trying to reboot, the PSU will power on but the PC will not post and will not display.
This will continue until 2-4 hours have passed since the PC shut down.

The CPU Temp was 44C and MB was 39C at the time of the crash.

Please help if anyone has any ideas! I'm wondering if something is overheating or if the PSU is not enough to handle all that I have.

Thanks!!


ASUS M3N72-D
AMD Phenom 9600 Quad Core (AM2 )
4GB Memory
500W PSU
2x eVGA GeForce 8800GTX (SLI)

A pair of 8800GTX's need about 20 amps at 12 volts. The CPU will use around 8 - 10 amps. Depending on the brand of the PSU, that will be close to the limit of the 12 volt rail.

Next, and commonly overlooked, most PSU's are rated at maximum power at 25 C. PSU performance curves that I have seen indicate that such a PSU need to be derated about 1% per degree C over the rating temperature. That means that the PSU produces less power the warmer it gets.

Assuming the internal PSU temps reach 40 C, a not unreasonable level, will be producing around 425 watts. And it won't come back up until it has had time to cool.

My two favorite brands, Antec and Corsair, rate their PSU's at 50 C.

Well I decided not to post a heap of stuff about how much current ... I just did the calcs myself ... and passed on the recommendation.

Simple enough ...

Lets just try to get the OP's problem solved eh?

That way he might hang around and join in the fun.

BoM is paying me to attract and keep new customers here ... get with the program people !!

Ooops ... lol.