Problem with homebuild PC

Hey guys, i ran into a problem with my homemade PC and i don't know exactly what is wrong with it.

The problem is the following:

Whenever i play these hot games with killer graphics (F.E.A.R. and Oblivion) with maxed out graphical settings and i quit the game i have to reboot the system. I tried using the benchmark from futuremark (3dmark 06) and when i came to the Pixel Shader 3.0 tests i was able to see the same problems happening again.


So what happens. When i quit FEAR/Oblivion or the PS 3.0 test is done and i return to windows the screen refreshes VERY SLOWLY. It's hard for me to explain what happens. For example i press the START button:

1. i press START button
2. screen turns black
3. START menu appears
4. i select programs (or any other thingie from the menu)
5. screen turns black
6. the selected thingie appears

and so on. Also this happens at a very low speed so it takes a while for me to open something i want.

After a reboot everything is fine. I also experienced random blue screens of death while playing Fear and Oblivion, i do not know if the problems are related.

The system is brand new and FEAR and Oblivion are the first games i played on my system.


AMD Athlon FX 57
DFI LanParty UT NF4 SLI-DR Expert
Creative X-FI Fatal1ty
Asus 7900 GTX
2x 1GB of Kingston memory (khx3200a)
PSU Antec TruePower 550W


So... in my oppinion it's something either wrong with my graphics card or the PSU cannot handle it because this happens ONLY when playing the most challenging games graphics wise (and with max settings).

I tried playing Call of Duty 2 with max settings and nothing happened so far.