VX 550w for 4850 Xfire

[Oldjim]

My existing VX550w would appear to be OK for two 4850 graphics cards in Xfire mode judging by the total system power demand under load reported here http://www.anandtech.com/video/showdoc.aspx?i=3338&p=5 as 335.7 watts. The VX550w has a 12v rail of 41 amps.
However it also says in the body of the report that

With two 4850s paired up in CrossFire, we once again ran into issues with our power supply. Our 1000W OCZ EliteXStream wasn't always enough for the dual-GPU setup and in Call of Duty 4 our system rebooted in the middle of our test at 2560 x 1600

Now I certainly don't expect a comment on a competitors power supply but that unit is supposed to have a single 12v rail of 80 amps.
Is there any obvious reason why my present unit wouldn't be adequate.

[PeterStoba]

It will run fine, they draw 350W in crossfire, and you have enough amps on the 12v

[shadowmaster]

Yeah I agree with above, your psu will be perfectly fine for 2*4850s in crossifre. TBH I'm not sure what that review means, that 1000W OCZ Psu (if working properely) would be able to handle 3*4850s in crossfire.

[Yellowbeard]

Yeah, I'd have to read that Anandtech article first. A true 1000w PSU should run 3+ of ANY video card made. THe VX550 will run your Crossfire setup easily.