Originally posted by m3trj
There's AGP and PCI-e. All AGP cards work in all AGP slots, and the same goes for PCI-e, but AGP won't work in PCI-e and vice versa.
That's right and they will work as long as the gfx card and mobo were made within 5 years of eachother and the slot is the same
Okay about the number of cards
In an AGP system: You can usually have 1 AGP card and 1 PCI. You can even run more PCI cards if you really want.
In a PCI-E x16 System: You can run 1 PCI-E card and usually something in a PCI Slot:
In an SLI PCI-E x16 System: You can run 2 PCI-E cards and usually something in the PCI slot.
And the last but weird one, if a PCI-E system with two PCI-E slots, you can run two PCI-E cards in PCI-E x8 mode.