what on earth do you need 600 W for?
besides, this is a manufacturers forum so all advices you will get here is about products from Aquacomputer.
Why not the CoolCurrent (450 W).
BTW: W doesn't give any information about the quality of a PSU...
I don't know why he needs one, but I do know why I need one.

I had asked a while back about the Cool Current 450 and no one seemed to be able to give me the info I needed so I will ask again. Power as expressed in watts is normally rated at a specific temperature. The problem is that some manufacturers will rate their big bad old 500 watt supplies at say 35 degrees Centigrade. The problem is that most computer PSU's operate at about 45-50 degrees so how you rate your supply can inflate your wattage claims, okay?
So what we need to know is at what temperature does the Cool Current 450 claim to have 450 watts of power? We also need to know how may rails or separate circuits there are for the 12v lines if more than one. How many amps are capable on each voltage circuit as well.
Now as to why we need such powerful PSU's I can only say that big processors, SLI rigs w/ 6800 Ultras, and a lot of 10-15,000 RPM drives makes for some very hungry computer boxes.