A lot depends upon the rendering requirements of the game (more realistic video == more bandwidth required) and resolution you want to use. Most recent cards that are in the under $200 USD category will do quite nicely unless your wishes are to play the most current top-end games. In that case, you will spend more like $500 USD for such cards. Myself, I like nVidia cards. Others prefer AMD devices. One of my friends and former colleages who is a serious gamer likes nVidia cards. You can connect 2 together with what is called SLI in order to get even higher performance. These cards suck up a lot of power, so you will want a system with at least a 1KW power supply, and lots of cooling! Cheap? Not! So, what is your budget for an entire system? Let us know, and we can better advise you as to what you can get for that investment.