Below is a breakdown of what types of card busses are supported by EVGA grapgics cards and how to identify them on site.

PCIE is the current stardard, and all high end cards are on this bus type.  Keep in mind that whilke GPUs can run on 8x, they are designed for 16x.  And as such wll not run, or even plug into, propperly, a PCIE 1x, 2x, 4x slot.

PCI is an older slot that is being phased out, and is currently only being used on lower series (fx 5000 and 6000) the the bottom end of current cards (8400 GS PCI, 9400 GT PCI, and 9500 GT PCI).  This is still widely use in low to mid range systems that are needing extra monitors or a GPU with a little bit more power, and are not equipped with slots to accomodate the top flight cards.  This slot is slowly being phased out, but will still be around for some time.

AGP was the old standard for top end graphics cards, but all curent designs have greatly exceeded the capabilities of the AGP slot, and it was retired several years ago.  Currently we make the FX 5200 AGP and the 6200 AGP to accomodate older systems, but keep in mind, that the AGP slot is effectively dead and gone, there are a limitted amount of cards out there still on this bus, and non are top end.