What graphics card will fit in my computer?

I would rate it as "Not possible." If this is what you have: a href="http://www.techradar.com/reviews/pc-mac/laptops-portable-pcs/laptops-and-netbooks/asus-x58l-609781/review" rel="nofollow"http://www.techradar.com/reviews/pc-mac/…/a , it's a laptop. With very rare exception (e.g., $4000 Alienware laptops) there is no way to upgrade the graphics on a laptop. The graphics chip is soldered to the motherboard and unlike desktop machines there are no standard PCI-Express slots in which to plug a new graphics card. If you want better graphics .. buy a new laptop.