Actually, just because it's rated 600w doesn't mean it's pulling 600w all the time. Think of wattage as the max speed on your spedometer. You're likely to only really be pulling ~300w at load.
Ah I see, thanks for the clarification!
Yeah I always over buy on PSUs, my main system has 1000W but realistically at full load it might use 400W... maybe. But I bought it because I wanted to run triple SLI at some point. Still waiting for used gtx680s to go down in price.
