Depending on the motherboard (I’d suggest the 990 chipset) you should be able to do most games at medium to high settings. AMD chipsets don’t do PCIe 3.0 so Ultra on the latest games might be difficult. Crysis 2 you should be able to do at medium to high, I don’t play BF3 so I couldn’t say.
Some cards by different manufacturers can have different settings but normally if they do they will be marked as superclocked or some such.
I’d go with the XFX. I’ve own a few and they are normally very dependable.
I don't want to bring you down but those cards will not play crysis 2 or bf3 at high settings assuming at 1080p. The cpu is good and will do justice for quite a while yet in games.From experiences a 7770 will play bf3 at 1080p textures on ultra everything else on medium with no aa at 55-65 fps and will play crysis 2 on its lowest preset at 1080p between 50-55 fps,so i wouldn't be looking at anything under that if you want to be able to play games on high unless your playing at less than 1080p. I was running pci 2.0, currently there is little to no performance increase from using pci 2.0 vs 3.0 and 2.0 and 3.0 cards are back words compatible