PSU [SMPS] for radeon 4850 x2 crossfire ?

Does 4850 x2 crossfire mean you have 4 4850s?
If so, yes you cannot run those four cards on 650W PSU

But,
If you have 2 of them, you are more than safe to go.



GooD LucK

Considering each 4850x2 consuming 250W,two of them would need 500W..Since around 95% power is drawn from 12v rails you would need a power supply which can provide at least 40amps on the 12v rails...Further your processor consumes around 200w under full load...current required on 12v rail by cpu is 16Amps..Therefore the net current drawn by 2 gpu+1 Cpu on 12v rails is 56amps..Hence you need a psu which can provide at least 60Amps on 12v rails

Don't Quad fire HD 4850x2.
Even a single card is power hog. That card emit a lot of heat.

U will gain a little performance on quadfire, just use 2 of them and crossfire.
A single 4850 itself produce lot of heat, so u wouldn't take a risk of overheating...