Power supply - how much do I need?

[sinkro]

I'm deciding between a seasonic x560 or x660 and I'm wondering if it's worth going over to the 660. I have the following components:

Intel i5-2500k
HIS Radeon HD 6950
Crucial M4 SSD
8 gig DDR3 RAM
Using 3-4 USB drives, and I have 4 USB 3.0.

I might overclock the processor. The GPU comes overclocked so I don't see a reason why I would do that. I tried calculating my power consumption assuming max load or near max load and 560 doesn't seem to cut it. Your thoughts?

 

[ko888]

For a system using a single Radeon HD 6950 graphics card AMD specifies a minimum of a 500 Watt or greater power supply. The power supply should also have a combined +12 Volt continuous current rating of 32 Amps or greater and have at least two 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.

The Seasonic X-Series X-560 (SS-560KM), with its combined +12 Volt continuous current rating of 46 Amps and with two (6+2)-pin PCI Express supplementary power connectors, is more than sufficient to power your system configuration with a single Radeon HD 6950. There is even enough reserve capacity to handle overclocking of the CPU.

The Seasonic X-Series X-660 (SS-660KM), with its combined +12 Volt continuous current rating of 54 Amps and with four (6+2)-pin PCI Express supplementary power connectors, is also more than sufficient to power your system configuration with a single Radeon HD 6950 and handle any overclocking of the CPU and GPU.

 

[sinkro]

Best answer selected by sinkro.