|I don't know of an A6 that runs at 3.5Ghz. Can you look closer?|
Appears you have the basics of a fair gaming system but we are going to need more details...
...motherboard manufacturer and model number
...what video? The gpu on the A6?
...RAM manufacturer and number
...stuff like that
Sounds like you may only need the video card kuwese linked to in response #1.
You could be done with your "...$400 gaming pc that can run games pretty well..." for about a hundred bucks and happy as a clam. That's why riider ask you for that information.