Issue with multiple screens

Hello everybody, I just got my new notebook a Lenovo Extreme Gen 3 but I’m having some issues with my monitor configuration and I hope somebody can help me out.

I’ve installed the video-hybrid-intel-nvidia-450xx-prime driver in the latest version and use the 5.8 kernel.

In addition to my integrated 4k OLED screen in my notebook I try to use 2 Dell screens (27"). One connected via HDMI, the other one via USB-C.

The screens work even though the performance is pretty bad. Moving the mouse around is not quite fluent.

But I have 2 real big issues:

  1. Monitors suffer from overscanning (at least I think it’s called that)

On all 3 screens maximizing a window doesn’t show the full window, it goes much below the visible screen (on every monitor). I’ve read that this should be solved with xrandr --set underscan on but that gives me the error BadName (named color or font does not exist).

  1. Scaling

I can either have the 2 external monitors readable when setting the scale to 100% or the internal monitor when setting it to 200%. Seems that this setting can’t be independent by monitor, but that’s necessary if I use a combination of DPI screens.

I hope somebody can help me out. Thank you in advance

  1. Does this show up in a screenshot too? If not: it’s a monitor issue, not a DE issue and you need to change the monitor settings.
    (more info needed: xrandr and cvt output at a minimum)
  2. Yup, that’s by design a known problem: the only way to have different scaling is to change resolutions on the offending monitor. (probably the laptop screen)

As you didn’t provide any details, I can’t tell you what to do exactly, but most people end up setting their laptop screen to FHD from UHD (or HD from FHD) when using larger external monitors, or just closing the laptop lid and solely using the external screens…


i know nvidia settings have underscanning options and other stuff. you just have to type nvidia-settings in the terminal and it will open. if its not installed you can install it with nvidia-smi i believe.

The first issue is the limitation of the current implimintation of the Reverse PRIME in the nvidia driver, which makes external screens work in the X1 Extreme (I have a Gen 2). To use the external monitors normally, the best course of action is the stop using the hybrid mhwd setup, and instead use optimus-manager in Nvidia mode. The external screens will work flawlessly with optimal performance. The trade off is that whenever you need extra battery life, you have to switch to intel mode manually by relogging into the session.

The fact is that currently the true hybrid graphics solution is not ready for any real usage on the laptops with external outputs wired to the GPU, regardless of what Lenovo certifications or user anecdotes would lead you to believe. But the optimus-manager manual switching works very well, save for minor KDE-related issues with Nvidia.

The second issue is the limitation of the xorg design. There are 2 ways around it:

  1. Change the resolution of the internal screen (that’s what I do on my machine)
  2. Use xrandr --scale 2x2 option on the external screen. This again works only in full Nvidia mode and does not work with reverse Prime, Bumblebee or any other hybrid solution. I personally don’t like it because it makes the picture on the external screeen too fuzzy.

Changing resolution doesn’t do that.

P.S. I’m worse: I run on nVidia only, no Intel here… :man_shrugging:

Yep, that’s why I use the first solution. Technically downscaling the resolution from UHD to FHD on the internal screen also introduces some blur on the internal screen, but it is nowhere near as pronounced as from upscaling an FHD external screen to UHD.

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