Which graphics card does my cpu support?

That's a old K8 you can tell by the M400 chip set...its probably a socket 754...the for runner of the AM2 it only came with 1 AGP 8X socket so your kind of stuck with that. here are a few graphics cards that will fit your slot...BUT...check your PSU for enough power and the right connectors before you buy a card...a href="http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=100007709%20600007850&IsNodeId=1&name=AGP%204X%2f8X" rel="nofollow"http://www.newegg.com/Product/ProductLis…/a