Clevo P650 issue with DisplayPort and hybrid graphics

Hi all

Ever since updating to Windows 10 CU (and still now on FCU) I've had an issue relating to the GPU on hybrid mode.

On a fresh boot, the dGPU will go to sleep as expected when not in use. However, if I plug in my monitor (displayport Benq xl2430T) and then later unplug it, the dGPU will always stay awake. Oftentimes, using the nvidia activity monitor I will notice that a lot of apps, including background apps like Dropbox, would have moved onto the dGPU even though it's set to use integrated only in the nvidia control panel. If I kill all those apps, the dGPU still does not sleep until:
a) I kill explorer.exe (sometimes works)
b) log off/on or reboot (always works)
But then plugging the monitor back in brings the issue back.

Another issue is that after the monitor has been unplugged and then plugged back in again, the refresh rate on the monitor is really bad, it's basically stuttering all the time unless I set the displays to extend across both monitor and laptop screen.

I've tried clean installing drivers and everything but these issues are really annoying and I can't figure out how to overcome them.

Anyone has any ideas?

Thanks

 

The external monitor ports are connected to the dGPU ONLY, so when you use them, the unit will flip to Discrete mode. Seems you need to reboot to get back to iGPU mode.

 

When running the displayport, the dGPU powers the monitor and the iGPU powers the internal screen. I assumed if you unplugged, it would revert, because generally killing and restarting explorer will fix it. So it seems more like something is causing the dGPU to remain active even after the monitor is unplugged.

 

This is completely wrong.

The DISCRETE/DXHYBRID switch re-routes the primary display (physical mux switch chip) and activates/deactivates the iGPU. It cannot change state while the system is running. All you can do is queue up the change in software for the next reboot.

This sounds like a simple bug with the Nvidia 3D application detection and probably exists for any Optimus laptops which use external ports directly connected to the NV GPU (quite common now as VR support practically requires that to happen).

 

Probably it then. Any possible workaround that you might know of?
Thanks

 

LogOff/LogOn is probably the best bet. The GPU context switching is offloaded to Windows since Win8.1 which is probably half the issue. Once you connect the external display, explorer is initialised on the Nvidia GPU and there's probably no functionality to reverse that.

Alternatively, if you're not gaming on the external screen and it's only 1080p, you could try a USB video adapter instead. That way the NV GPU is not being used.

 

Hmm, makes sense. It's a 144 Hz monitor which I do use for gaming, so I don't think USB will be an option. Guess I'll just log off/on. Thanks for your help.

 

Found another workaround: disable and re-enable dGPU in device manager... seems to do the trick without requiring a reboot/logoff.

 

Doesn't seem like any one else has/cares for this issue, but I've written a small tool which runs in the background and will reset your GPU (disable/reenable) when the laptop is unplugged, or if a hotkey is pressed. In case there is anyone who wants, let me know and I'll put it online somewhere.