I'm having issues with using SLI GTX 580 graphics cards with this power supply ST1200-G. Basically when they are under heavy use e.g games, benchmarking, stress testing, my screen goes black with no signal and audio makes a buzzing sound, I can't do anything with my computer apart from a hard shutdown/restart. The event log says there's been kernel power issues its always the 0x00000116 - but that could be caused be the hard shutdown. Using one graphics card works fine as I stress tested them both. I recently tested them through SLI on furmark and when I lowered the voltage of the cards through MSI afterburner it didn't crash, which leads me to believe that the power supply is the problem.
All graphics card drivers are up to date and I have a surge protector. The surge protector I thought was the original problem because I plugged it directly into the wall and its been working for weeks but then when I attempted an overclock afew days ago its returned to the same problem.
Other fixes I've tried is video card bios format/update, underclocking which works for a while and lowering graphic settings.
i7 950 @4.00 HT liquid cooled
patriot sector 7 6gb 2gb x 3 8-8-8-24 2t
2x msi gtx 580 twin frozr 2 liquid cooled
ocz vertex 2 60gb =OS
ocz vertex 3 120gb=games
silver stone strider gold 1200