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I turned off my Nvidia GPU with prime-select today after a few weeks running dual-screen on GPU. The laptop is a Thinkpad P51 / Intel Skylake Xeon / Nvidia Optimus Quadro M2000 with Ubuntu 18.04 up to date, Nvidia driver is 390.

The first thing I noticed after rebooting was the HDMI exteral screen was still on, which is not possible since the HDMI port is wired to the GPU and can't work with the GPU off. So, nvidia-settings and nvidia-prime show that the active GPU is Intel, but in fact Nvidia is on.

Looking at the powertop output, my computer runs at 19-22 W idle and burns its battery in 4h, which is typical of the Nvidia GPU (on a fresh install, I did tests with Intel at around 9 W idle and it lasted almost 10h on battery).

Of course, I did all the apt autoremove nvidia* dance twice, reinstalled xorg etc. My GPU is on whatever I do. How can I force it off ?

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In 18.04, prime select no longer uses bbswitch to turn off the nvidia card. It uses a kernel feature 'vgaswitcheroo'. There are quite a few bug reports that it doesn't work. https://bugs.launchpad.net/ubuntu/+source/nvidia-prime/+bug/1765363

You will also find tips and workarounds that may help you.

bbswitch actually still works fine with 18.04.

Based on someone else's work, I have a solution here: https://github.com/timrichardson/Prime-Ubuntu-18.04 which uses bbswitch to power off the nvidia card.

It also does no-reboot changes between intel and hybrid mode.

It works really well on a modern Optimus laptop, and reasonably well on a 2011 Optimus laptop.

Update: 18.10 has a revised approach by the Ubuntu dev, which internalises the bbswitch approach (so it's a big change for the better). On my laptop, it powers off the nvidia card correctly and does it without needing a reboot, but there are some other rough edges still and I don't think it is ready for 18.04 backporting just yet, although that is not my call of course.

Second update (late October 2018): In my experience, the backport of the 18.10 work to 18.04.1 is good enough now. You have to use the command line to go from intel to nvidia (prime select nvidia) since the nvidia control panel doesn't launch, but it's fast and reliable on my two Optimus laptops. I have stopped using the code from my repository above.

  • Could you clarify your latest update. On an up to date elementary OS Juno (Ubuntu 18.04 LTS) lshw -c video still lists an UNCLAIMED Nvidia card. Is there anything extra we need to do to get this working properly? How did you verify it works? – Peter Uithoven Nov 4 '18 at 15:36
  • Hi Peter, I don't use Juno ... What nvidia-prime package do you have? I verify that it works by the power usage, it's definitely working for me. If your card is not working, you can report a bug against the Ubuntu package, Alberto will look at it for sure. – Tim Richardson Nov 4 '18 at 15:57
  • Version: 0.8.8.1. You? For reference: ubuntuupdates.org/package/core/bionic/main/updates/nvidia-prime Is it still listed under lshw -c video for you? With unclaimed? – Peter Uithoven Nov 4 '18 at 18:08
  • Now running 0.8.8.2 – Peter Uithoven Nov 14 '18 at 23:56
  • Hi Peter I mostly use Ubuntu 18.10 on my Optimus laptop, if you are on the Ubuntu 18.04 base then does my repo work? – Tim Richardson Nov 15 '18 at 2:48

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