Hey Guys,
 
Im new to this page but, I have just finished building my 3rd computer and i am having some issues
It is a:
 
Intel Extreme CPU QX9650
XFX 790i Ultra SLI Board
2 Dimms = 4gb DDR3 1333Mhz Patriot Memory
EVGA 8800 GTS 512MB Video Card
4 120mm fans, 1 exhaust fan, pci slot fan
2 HDDs (1 SATA & 1 EIDE)
Windows Vista Home Premium 64-bit
PSU: 550Watt Ultra X-connect
 
I almost have this sytem running perfectly,  
but whle playing high end games it freezes up.
 
I have replaced every single part including, M/b, DVD Drive, Memory,  
and still nothing corrects this problem.
 
Is it possible that THE PSU is not strong enough or just a crappy brand?
any recommendations?

well 550w should be enough but I have heard AWEFUL things about Ultra PSU's.  Also you should consider 550w sustained compared to 550w max, as well as capacitor aging.  You should definately get like a corsair 650 or a PC power and cooling 610 or so.  you will be much happier with one of those.

^agreed

 
 
I prefer Seasonic's PSUs, who, by the way, makes those Corsair and PC Power & Colling PSUs.

Thanks a lot,
 
i will definitely try this out and let you know how it goes.
hope it fixes the problem