For a system using a single GeForce GTX 560 Ti graphics card NVIDIA specifies a minimum of a 500 Watt or greater power supply that has a combined +12 Volt continuous current rating of 30 Amps or greater and that has at least two 6-pin PCI Express supplementary power connectors.
For a system using two GeForce GTX 560 Ti graphics cards in 2-way SLI mode NVIDIA specifies a minimum of a 700 Watt or greater power supply that has a combined +12 Volt continuous current rating of 53 Amps or greater and that has at least four 6-pin PCI Express supplementary power connectors.
Total Power Supply Wattage is NOT the crucial factor in power supply selection!!! Total Continuous Amperage Available on the +12V Rail(s) is the most important factor.
Further overclocking of the CPU and/or GPU(s) will require an additional increase to the combined +12 Volt continuous current ratings, recommended above, to meet the increase in power required for the overclock. The additional amount required will depend on the magnitude of the overclock you are trying to achieve.
You were looking at a Thermaltake 600W in one of your other posts. Avoid the TR2 Series, TR2 RX Series, Pure Power Series, Lite Power Series and Smart Series. Some of them even have liar labels and are unable deliver the power stated on the label.
Most of the various Tough Power Series models are good.
okay the rest are: evga gtx 560 ti (FPB), 8gb corsair vengeance DDR3, wd hard drive 2tb, 3 cold cathodes, 4 channel fan controller,asus p8z68v-lx motherboard, asus cd driver and the 600w psu that i already have