I've trying to pus my GTX 460 Hawks (SLI) recently but have found after about 810mHz during Heaven Demo the computer just freezes. Nothing pops up or crashes and I have to do a cold reboot. I thought it might be a PSU issue with only 750w but I saw an entry of someone pushing their CPU and GPUs on a 750w PSU. Is this really a problem of low power or can I fix it by upping the voltage on the cards?
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Hi and welcome to Tom's forum.
Your problems are because the GPU isn't stable at those clocks, you need add more voltage to the CPU and try again for stability.
Providing you have a reasonable PSU, 750w is MORE THAN ENOUGH for 460+cpu, you could probably even push SLI on that.