Build looks good you could get a 750tx corsair psu to run that but if you are going to crossfire then 1kw will be good with those cards. Why the ide optical drive. Replace it with a sata.
Be careful of the fans with that ram they can get in the way of things. I opted to get OCZ Reaper 1066 ram for my system instead of those cause I didn't like the fan system.
Back to the psu find yourself a singel rail 1kw psu for the build Corsair 1000hx is one and then Silverstone makes some as well.