Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I'm looking at building a system that supports VT-d so I can pass through a high powered loud video card to a Xen/KVM/whatever VM (host will be Linux based). However, when I'm not using the VM I want to turn the video card off so its fan does not run. The card will not be used when the VM isn't running.

Anyone know if this is possible? The PCI-Express hot-plug specification allows cutting power to specific slots but I have never heard of anyone doing it with a video card and my searches for information have turned up nothing.

share|improve this question

In theory the specification allows it; in practice your motherboard would have to expose the functionality to something application that would let you adjust this, and I have never seen nor heard of either.

share|improve this answer
This can't be the complete set of possibilities. Besides the mentioned hot-plug specifications which remains to be investigated (also for…) it'd be possible to write a PCIe driver that checks whether the card is plugged or not for every processing cycle. That'd be very inefficient, but possible. – Karl Richter Jun 14 '15 at 9:31

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.