"Recommended Power Supply
Here is Guru3D's power supply recommendation on the GeForce 500 series:
GeForce GTX 560 Ti - On your average system the card requires you to have a 500 Watt power supply unit.
If you are going to overclock the CPU or GPU, then we do recommend that you purchase something with some more stamina."http://www.guru3d.com/article/palit-geforce-gtx-560-ti-twin-light-le-review/7