Im thinking about buying r9 280 dual x oc crossfire or msi gaming r9 290 with fx8350. 990 fx killer h80i what would give me better performance,never used crossfire tbh,some People say it has issues but arent they fixed stuttering with 14.4 and 14.6 is out today? And is xfx pro 750 able to power crossfire of two r9 280 and other components with leaving headroom to oc gpus and cpu,also if i go with single r9 290 and.buy xfx 850w could i add later one more r9 290 on.that psu? This rig would be for gaming recording and rendering