Hi i just want to ask if my PSU will be sufficient enough to run 2x Sapphire 7850 not OC ed.? My PSU was a FSP Raider 650watts. When i checked a PSU calculator site it gives me 440watts including all of my hardware listed on it with 2x 7850 selected xfire, but i just dont wanna rely on it, i just want to make sure that there will be no problems when i buy another 7850.
considering the OC edition is tested to suck about 250W, let's say 230W for non-OC, x2=460W just for the video cards. Add another 100W for whatever else you have (not knowing) and you're cutting it close. You don't want to run your PSU any more than at 50% if you don't have to, as that's normally the sweet spot for efficiency - depending on the model you have... you can check here - http://www.plugloadsolutions.com/80PlusPowerSuppliesDet...
If I were you I'd get an 850W just to have some headroom, and whatever else you wanna do, like OC in the future.
why don't you hook up a power meter and get a load reading of what your system is sucking - then you'll know if you have room, don't forget the closer you get to 80% load on the PSU, the more heat and fan noise you hear, so not knowing your case layout, might be an issue with adding heat to the already heated inside with 2 cards running