So, I have the Optiplex 755 from dell. 2.93ghz processor, 4g ram, 500g storage. It has intel(r) GMA 3100, this is terrible. I want better, most threads are created by people with Optiplexs that have much smaller cases. I want a powerful card that will fit this larger case without missing out on potential power by getting a card too small or less capable. Any suggestions? For further reference there are four cases created for optiplex I have the case a step down from the largest and I was looking at ASUS Radeon HD 6450, is this too large?