Can i run some higher video cards on lower speed PCI-Express slots like 8x, 4x etchttp://en.wikipedia.org/wiki/PCI-Express
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A connection between any two PCIe devices is known as a "link", and is built up from a collection of 1 or more lanes. All devices must minimally support single-lane (x1) link. Devices may optionally support wider LINKS composed of 2, 4, 8, 12, 16, or 32 lanes. This allows for very good compatibility in two ways. A PCIe card will physically fit (and work correctly) in any slot that is at least as large as it is (e.g. an x1 card will work in an x4 or x16 slot), and a slot of a large physical size (e.g. x16) can be wired electrically with fewer lanes (e.g. x1 or x8; however, it must still provide the power and ground connections REQUIRED by the larger physical slot size). In both cases, the PCIe link will negotiate the highest mutually supported number of lanes. It is not, however, possible for a device to operate in a slot that is physically smaller than it (e.g. an x4 card can't fit in a slot which is physically an x1 slot — THOUGH it could operate in a x4 slot wired with only 1 lane).