We need details. List Exact model of the PSU, HSF, and your GPU's. Please list your temps on your cpu and gpu while gaming as well.
A pair of GTX560ti's will pull about 32 amps. Figure another 10 amps for an OC'd CPU. That's about 500 watts. Figure another 100 - 150 watts for everything else coupled with a very good PSU gives you plenty of power.
Some motherboards are unhappy with RAM running faster than 1333 MHz.