ASUS Crossfire IV Formula
AMD Phenom II x6 1090T 3.2GHz
8Gb G.SKILL Rip Jaw
ASUS ENGTX480 1536Mb
OCZ stealthxstream ultra-silent 750W
Cooler Master HAF932 Full Tower
Seagate 2TB Green 5400RPM (storage)
Western Digital 500Gb Blue 7200RPM (primary)
I've had a lot of issues of getting the RAM sticks to pass memtest86 so I kept exchanging them. Eventually I got two perfect ones (tech guys told me I just got bad luck).
I'm running Windows 7 Enterprise with SP1 and all updates. BIOS is updated to the most recent stable version 1304 I believe. Video and chipset drivers are up to date.
The problem is that when I tried to play Crysis 2 or Mafia 2, PC would simply reboot sometimes. At some point it went away and I was able to even beat Crysis 2. But now the problem came back and PC restarts once it reaches particular point. This only happens in very demanding games, once it warms up. I leave my PC over night doing stuff - no problem.
My temperatures under highest load:
CPU ~44 C
Video ~80 C
Please suggest what should I test as I see no other possibility other than the PSU (I know nothing about OCZ PSU's). Maybe my system is underpowered? Pretty desperate....
It could be the power button on the case. Cooler Master had numerous issues with it on HAF cases. (Though, I thought they fixed it...) Try using the reset button instead of the power button, or flipping the power button's motherboard connector itself.
Other than that, I might suspect the PSU as well. OCZ's PSUs do tend to have somewhat limiting multi-rail power distribution divisions, but I can't find a decent review for the StealthXstream 750. Any chance both of the PCIe power cables are actually on the exact same rail? (12V4 perhaps?) If so, try switching one to 12V3 using a 2xMOLEX-to-PCIe 6-pin adapter and see what happens.
That psu has been discontinued for a long time. The only thing that I can find that is similar is the new version, the OCZ StealthXStream 2 700W. And from what I can tell from the spec sheet and the wattage chart, Razbery is correct in assuming that you're running both PCIe connectors off the same rail. Considering this is a budget psu running a very non-budget oriented card (the 480 is probably the most power hungry card ever built), you need to make sure that you're feeding it at least 2 of the rails.
See this other thread I found of someone else having the same trouble. It might help you make more sense of it.
So, uh, long story short, Razbery is correct. Lol why I post...
P.S. this is probably what your wattage chart looks like: