Nvidia 450.57 reverse prime on ThinkPad X1 Extreme 2

1 Like

Hy @bob418 can you explain a bit what this is about?
Does it allow Windows-like Optimus behaviour for nvidia + igpu ? Aka complete disable / enable of nvidia graphics on the fly?

I think it’s both GPUs on all the time (power-consumption is not at it’s best), but you can switch on the fly…

Although it would be cool @nate if you’re right :slight_smile:

welcome

I have the same discrete GPU and have this on my system:

and my xorg.conf:

$ cat /etc/X11/xorg.conf                            
 
Section "ServerLayout"
  Identifier "layout"
  Screen 0 "iGPU"
  Option "AllowNVIDIAGPUScreens"
EndSection

Section "Device"
  Identifier "iGPU"
  Driver "modesetting"
  BusID "PCI:0:2:0"
EndSection

Section "Screen"
  Identifier "iGPU"
  Device "iGPU"
EndSection

Section "Device"
  Identifier "dGPU"
  Driver "nvidia"
  BusID "PCI:3:0:0"
  Option "AllowEmptyInitialConfiguration"
  Option "NVreg_DynamicPowerManagement=0x02"
EndSection%                  

(Although I’m not sure those two lines beginning with Option do anything. I felt the need to add them somewhere :slight_smile: They’re supposed to allow the GPU to go into the lowest power state when not in use.)
What bothers me most about this setup is that the GPU indicator led stays amber, which indicates the nVIDIA card is always on. Which means about 1-2W of drawn power at all times just by having the card sit there and do nothing. For a 8-9W idle power draw for the whole machine that translates to about 10% extraneous power draw. Or that much less battery life.
Because I keep my machine 99.9% of time plugged in, I don’t really mind that much, still, I’d love to see that GPU led turn white.

Anther question. Does the 450.xx driver bring some notable improvements to the switching behaviour compared to the 440.xx?

Now I just need the new Nvidia driver (it seems only Arch has it in repository), I don’t need to install any extra stuff (optimus-switch or optimus-manager). The system automatically enable Nvidia graphics when connecting external monitor, and turns off Nvidia after disconnecting. I can keep my computer running my workflow without interruption.

I’m not sure about Windows. On my EndeavourOS setup, it consumes 2-3w when off and 9-12w when on.

The reverse PRIME with the driver 450.57 is not perfect yet. It requires external monitor has the same resolution as my laptop’s. Previously I only have FHD monitor. But today I received my new 4K portable monitor. The setup has worked for 10 hours and so far so good.

On my EndeavourOS setup, it consumes 2-3 w when nvidia is off and 9-12 w when it’s on. The good part is I don’t need to do anything, the dGPU auto switches when connecting/disconnecting external monitor.

The 440.xx in hybrid mode can run apps with Nvidia, but can’t drive external monitor via Nvidia. The 450.xx can drive external monitor when needed (reverse PRIME). It still has bugs. But for my usage, it’s already good enough.

Interesting use case. thanks for sharing.

I put my reverse Prime setup to Sleep last night. No problem to wake up this morning. :smile:

1 Like

wait next release kernel 5.8

Improved power-savings for systems with PCIe to PCI/PCI-X bridges

Nice to hear the info. Arch should be 1st to get the new kernel. :grin: