For a system
using a single GeForce GTX 560
graphics card NVIDIA specifies a minimum of a 450 Watt or greater power supply that has a combined +12 Volt continuous current rating of 24 Amps or greater
and that has at least two 6-pin PCI Express supplementary power connectors
Total Power Supply Wattage is NOT a crucial factor in power supply selection!!! Total Continuous Amperage Available on the +12V Rail(s) is the most important.
Even the Antec EarthWatts Platinum Series 450W (EA-450 Platinum)
, with its combined +12 Volt continuous current rating of 34 Amps
and with its two (6+2)-pin PCI Express supplementary power connectors
, is more than sufficient
to power your system with a single GeForce GTX 560.
A single (4+4)-Pin ATX/EPS connector connected to the motherboard is more than sufficient for the Core i7-2600 CPU that you are using.