I was just worried that the Extreme 4 wouldn't have enough support to hold the RAM & the cpu cooler but if you guys give me the OK I'll go with the Extreme 4.
As for the PSU I plan to get another HIS 2gb gpu and crossfire it with the other one I'll already have, this is where my concern comes in with the 750W PSU.
I don't want to get an ungodly powerful PSU but I don't want to undershoot the wattage either.
Would this PSU support the addition of another gpu for crossfire?
750w is more than enough for a pair of 7850's. With 2 of them, your system at max load will draw around 400w.