PCI Express Power Constraints
All four PCI Express slots conform to the PCI Express Spec Common Electromechanical Specification 1.1. Slots one and two also conform to the PCI Express x16 150W-ATX Specification 1.0 for power through the two auxiliary power connectors (shown in Figure 1) for 12 V at 6.25 A max. If a PCI Express card installed in slot one requires auxiliary power, connect the booster cable to the lower auxiliary power connector. If a PCI Express card installed in slot two requires auxiliary power, connect the booster cable to the upper auxiliary power connector.
For information on PCI Express specifications and design guides, refer to PCI-SIG.
Each PCI Express slot provides 3.3 V and 12 V power rails. On the 3.3 V rail, each slot may use a maximum of 10 W. On the 12 V rail, each slot may use a maximum of 65 W (not including auxiliary power), subject to the total wattage rules listed below.
When populating the four PCI Express slots, you need to conform to the following total wattage rules:
Slots one and two (not including aux power), max slot power per slot: 75 W
Slots three and four (not including aux power), max slot power per slot: 40 W
All four slots (not including aux power), max total power: 200 W
Max aux power per connector: 75 W
Max aux power for both connectors: 150 W
Max total PCI Express power (slot power and aux connector power): 300 W
