My 4890 is starting to get long in the tooth on 1920x1200 and I'm thinking about going 5850CF for decent value. However, all I can find is voltage req's and not Amp req's.
That being said all of the Voltage reqs for 5850's in CF is a 600W PSU, and I currently run a PC Power and Cooling 610W Silencer. So on the face of it I already meet the voltage req, but I'd feel much better knowing the Amp req.
FWIW my PSU has 49A on the 12v rail. And yes I know I would have to use molex to 6-pin to run 2 5850's.
For a single card they say 500watt for a dual card 600watt. With a 100watt difference it means that the extra card needs less than 9amps. It basically means that you will be fine with your PC Power and Cooling. It is much better than your average 600watt PSU.