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- Graphics card and PSU requirement 5 answers
If not, then what's the minimum? I have seen an 800 watts setup but I guess that's too much.
Put your planned configuration into one of the online power calculators and see.
E.g. Antec have one here: http://www.antec.outervision.com/
Going by some information on Bit Tech, if you have both cards running at full pelt then you will be close to 500W of power being consumed by the graphics cards alone. Considering that the CPU will likely be running fast too, then you will be close to the 560W that the power supply is providing. Add on the HDD, fans, etc, and I personally wouldn't go for 560W on a system.
Something to bear in mind when purchasing a power supply, however, is the quality of it. A budget 700W PSU for example would probably not provide enough power when it is put under heavy load. Spending a little more on a well-known branded PSU is more likely to guarantee that the PSU will provide enough power on all rails when under heavy load.