Hardware Reference
In-Depth Information
detect whether an 8-pin connector, a 6-pin connector, or no connector is attached.
Figure 18.35. PCI Express 8-pin (2×4) auxiliary 150W power supply connector.
Table 18.21. PCI Express 8-Pin (2×4) Auxiliary 150W Power Connector Pinout (Graphics Card
Socket)
Because of both the physical design as well as the use of the sense signals, the 6-pin power supply
connector plug is backward compatible with the 8-pin graphics card socket. This means that if your
graphics card has an 8-pin socket but your power supply has only 6-pin connectors available, you can
plug the 6-pin connector into the 8-pin socket using an offset arrangement, as shown in
Figure 18.36
.
The connectors are keyed such that they should only plug in the correct way, but be careful because
they can be forced together in an incorrect fashion, which can potentially damage the card.
Figure 18.36. Plugging a 6-pin power supply connector into an 8-pin graphics card power socket.
The sense signals are used so that the graphics card can detect what types of connector(s) are
attached, and therefore how much total power is available. For example, if a graphics card needs a
full 300W and has both an 8-pin and a 6-pin connector on board, if you were to attach two 6-pin
power supply connectors, the card would “sense” that it had only 225W available and, depending on
