i'm gonna be getting a used system from my uncle, (lenovo thinkcentre m58p 7220 agu.) and i don't know if the gpu upgrade will work or not. i'll be upgrading the ram to 6GB, and the gpu will be an asus geforce gt 640 1GB GDDR5 low profile. i've seen people have failing graphics cards before, and i need to know if this card will be compatible. if you think it's a waste of money, the total cost is $250, so it's not. i also plan to overclock the cpu, if possible. (i'll upgrade the cooler before i do that.) does anyone have any clue? any help is greatly appreciated!