750 watter is cool for SLI's 560's ....nVidia has certified numerous 650 watters for even twin 460's. With 570's and CPU / GFX overclocking, most would consider a 750 is a bit tight .... I'd want more headroom so as to main stable voltages (within 1% variation) under high OC's.
The following units get 10.0 ratings from jonnyguru.com
Antec SG-850 - $250
Antec CP-850 - $120
Corsair HX850 - $150 after $15 MIR
XFX Black Edition 850 - $130 after $20 MIR
I have used them all ..... of late though, only using the CP and the Blacks for obvious reasons.