GTA 4 was known for being pretty CPU heavy to my recollection. Dropping the GPU down a little and putting a little more into the CPU would probably help there, but it is only one game.
With the Gamma I'll go into what I dislike about it.
Flimsy side panels. They are very floppy and have a lot of bend to them, and I've seen much solider panels.
Width. It simply doesn't seem wide enough. The cable management area causes a lot of difficulty putting the side panel back on even if you run your wires cleanly. I've seen this complaint elsewhere as well if memory serves me. The SATA cable from the HDD going the other direction pushes on the side panel as well. Just seems like it would have benefited from an inch of added width.
Front panel design. This is more of a personal thing. I don't like how the front goes outward, and it being just a flush front end would appear much cleaner.
I just have more faith in Corsair, as well as it being $5 cheaper AR. 😉