I've been looking at various sites and received mixed responses on this topic, how many watts will I need for Crossfire 280X. I've been told many answers from 750w to 1100w. Any help would be greatly appreciated.
750 to 800 is enough for 99% of systems, what are your system specs?
Each card will pull approximately 200W in a gaming session at stock clocks.
250W each with an overclock.
300W each under a stress test - you'll never see that in a gaming session.
Truth is, if you have an efficient platform, you could easily crossfire on a good 650W PSU. However, I would recommend grabbing a 750W for the headroom. 750W is the rule of thumb for Crossfire/SLI-ing high-end GPUs.
Here's another advice, try to aim for the highest rated that you can afford. Bronze use to be the standard but recently because of the price drops of PSU i would recommend a 750W 80+Gold psu. Try not to skimp on the PSU this is the most important piece of hardware inside your PC.
for a crossfire 280x which will probably be worst case scenario @ 500W w/ overclock and all. Along with lets say an FX-8350 @ 125W, that's 625W. So yeah 750W would be the safe bet.
even on socket 2011, I went with a 750W gold rated PSU in anticipation for crossfiring 280Xs; assuming you are on AM3+, 1150 or 1155 I would say 750W would be absolutely fine.