Hello, i recently purchased a 27" iMac and everything has been going pretty well. But i have been trying to game on it and im finding the 6770m is barely cutting it at 2560 x 1440. So, what im asking is - should i return my iMac to Apple, and buy a Dell u2711 display and gaming PC. Or keep the iMac and hope for some sort of external GPU in the future.