PCI-SIG: PCI Express 4.0 will not offer more than 75W via the motherboard slot

Posted on Thursday, Aug 25 2016 @ 11:01 CEST by Thomas De Maesschalck
A couple of days ago one of the big stories was about how PCI Express 4.0 would dramatically increase the maximum motherboard power slot draw, and how this could eliminate PCIe power cables for video cards.

I had some doubts about the story as it didn't make a lot of sense, which was warranted as PCI-SIG now clarified that PCI Express 4.0 will not feature a slot power draw increase.

The goal is to increase the maximum power capabilities of PCI Express 4.0, but the motherboard power slot draw will remain at the current 75W limit:
PCI-SIG reached out to tell us that the power increase for PCI Express 4.0 will come from secondary connectors and not from the slot directly. They confirmed that we were initially told incorrect information. We have redacted a short passage from our original article that stated what were originally told, which is that the slot would provide at least 300W, and added clarification:

  • PCIe 3.0 max power capabilities: 75W from CEM + 225W from supplemental power connectors = 300W total
  • PCIe 4.0 max power capabilities: TBD

    New value ā€œPā€ = 75W from CEM + (P-75)W from supplemental power connectors.
  • PCIe 4 bandwidth

    About the Author

    Thomas De Maesschalck

    Thomas has been messing with computer since early childhood and firmly believes the Internet is the best thing since sliced bread. Enjoys playing with new tech, is fascinated by science, and passionate about financial markets. When not behind a computer, he can be found with running shoes on or lifting heavy weights in the weight room.

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