Currently, PCI Express X16 provides up to 75W of power for video cards, as opposed to the current 25W/42W allowed by AGP8X. Most modern cards already consume more than this amount, as evidenced by the extra power connectors that appear on today's AGP high-end video cards. This explains why most modern midrange PCI-Express videocards do not require extra power connectors, while their AGP counterparts do.

Given that both ATI and Nvidia have virtually switched over to PCI Express and that major graphics companies from 3Dlabs to XGI have already announced support for the architecture, it looks like AGP's days are inevitably drawing to a close. To further depreciate the value of your very expensive AGP cards, PCI Express X16 and 8x AGP slots cannot coexist properly on the same motherboard. This fact has not stopped various motherboard manufacturers from releasing ersatz PCIe/AGP solutions that use the PCI bus or part of the PCI Express bus. While this provides a better incentive to upgrade for AGP card users, it should be noted that these solutions do not provide the full bandwidth of a real AGP8x slot.

What makes up the PCI Express bus?