yeah the G45 has sli and CF support, however, it would probably not a great overclocker. for as far as that matters. its realy hard to find detailed information about powerphase design on Msi´s lower end intel boards realy..
If you stay on a single gpu setup, and you want a mobo with a 8+4 powerphase design and can do some overclocking then i´m thinking of the Asrock Z77 extreme 4 in your price range.