Although today’s video cards look like any other typical adapter cards, most recently created video cards fit in either of two types of motherboard slots:
Accelerated Graphics Port (AGP): AGP cards for today’s Athlon and Pentium computers use a dedicated AGP slot; no other adapter cards fit into this slot. (Refer to your motherboard manual or PC manual to make sure that you have an AGP slot before you buy an AGP video card.).
AGP video cards provide excellent performance, but they’ve largely been replaced in the marketplace by PCI Express cards.
PCI Express: PCI Express video cards can fit only into a dedicated PCI Express video card slot, so check your motherboard manual or PC manual to make sure that your machine can accept a PCI Express video card. However, after you install a PCI Express video card, you enjoy the fastest possible video performance; if you’re a hard-core gamer, make sure that any new machine you build or buy be equipped with a PCI Express video slot!