I wont claim to be an overclocking expert honestly your best bet would be to get a cheap video card and OC it alot of the DDR2 cards arent exactly stable when overclocking , a good cheap card would be an EVGA GT640 2GB DDR3 its what im using , i get 50 fps solid on max settings with just locking my voltage , when i Oc i get 25 - 30 frams running sweet fx and ENB tandem with 4000 + resolution texture packs from the nexus i would use GPUZ and PRECISION X in tandem and only do it little by little at a time and always do a benchmark test to make sure there are no graphical errors , also another good tip would be to defrag your saves i know it sounds wierd but the less time you computer spends going through its index for a save file the less stress it will have on game performance , not much of a forum person so if you want pics of my clock just shoot me an email or something