The PCI-SIG said last year that they were preparing an electromechanical specification for these types of cards, and in fact, according to a SIG slide presentation released ahead of the meeting, the specification was released at the end of March. Why do we need such a spec? As of now, the 150-watt spec is no longer sufficient, according to the SIG.
Besides the 2x3 connector defined in the 150W Graphics Spec 1.0, a new 2x4 connector is being defined for delivering power to the 225/300W cards, the SIG said.
Further information reveals the PCI Express 3.0 connector will be backwards compatible so your old PCI Express 2.0 graphics cards will still work on PCI Express 3.0 motherboards.
PCI Express 3.0 will be backwards-compatible with PCI Express 2.0, Yanes said. Since the connector will remain the same, the only difference should be in the electrical specifications. Note that while PCs will only require one connector, servers will still use two PCIe 3.0 connectors, the same as with PCIe 2.0.PCI Express 3.0 will offer double the PCI Express 2.0 bandwidth and the first products will appear sometime in the late 2010 timeframe.