if you pop open your computer, you will see the sound card, video card etc. most of these are in long white ports (PCI), but the AGP bus is the smaller black one. this is for high end graphics cards, although it is already starting to become outdated. I wouldn't recommend getting any type of PC mod if you're not comfortable rearranging your computer, let alone a graphics card. but if you do, make sure you have unused power supply cables, and that your motherboard actually has an AGP slot.