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msantos avatar Ubuntu

Screen tearing and weird artifacts on Ubuntu 20.04

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msantos

I have a lenovo thinkpad T14 and it works fine on Windows 10 but on Ubuntu 20.04 the overall performance, in terms of "graphical stuff", is bad. Watching videos or streams make the pc slow, it drops frames, etc... I managed to improve a lot by turning off the Nvidia GPU and use the integrated Intel graphics card only.

But the main problem that I'm trying to solve is that when using a second external monitor there's a lot of screen tearing and weird artifacts but only on the external monitors (turning off the built-in display makes no difference). Currently I'm using a USB-C to USB-C cable to connect one monitor and a DisplayPort to USB-C cable to connect the other monitor. But I've tried multiple combinations of HDMI cables, DP-DP using DP to USB-C adapter, and even daisy-chain the two monitors and it makes no difference as well. One monitor has a resolution of 2560x1440 and the other 1920x1080. I also tried to change the 1440p monitor to 1080p but it is the same. Probably not relevant but the 1080p monitor is the one using the USB-C to USB-C cable and besides video it also powers the laptop and works as a USB hub.

tearing: https://imgur.com/a/NHoXZcO weird artifacts: https://imgur.com/a/ClKtVuT

I have a friend with the same exact laptop that is running 3 external monitors, one 1440p and two 1080p, and one of the 1080p monitors is the exact same model as mine and he has no problems. So I'll guess that is some misconfiguration or driver problem in by pc. I also tried a fresh install of Ubuntu and I still have the same problem. Any suggestions would be cool :)

PS: I have read multiple threads about similar problems but all of them are focused in the nvidia gpu but I want to avoid using it because the performance when using it is terrible as mention above.

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Nmath avatar
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Nmath
"*and besides video it also powers the laptop and works as a USB hub*" - when you stop using the same cable for all of these unrelated tasks, does the issue persist?
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msantos avatar
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msantos
No, as I said I've tried multiple combinations of cables including not using a usb-c cable and problem persists. As long as two external monitors are connected I have this problem.
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Nmath avatar
ng flag
Nmath
For diagnostic purposes, create bootable Ubuntu media and see if the problem persists in a live session. I would also investigate the issue with your Nvidia GPU because this may be an XY problem. Turning off the dedicated GPU should not increase performance. The whole reason that it's in your device is to increase performance. They don't put extra expensive hardware in a computer to make it run worse. Does your friend use the dedicated GPU? Most laptop iGPUs cannot handle that many displays.
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msantos avatar
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msantos
I will try the live session but, answering your questions, my friend also uses the Intel GPU because when using the nvidia gpu the performance is really bad and it's not just me and him more people with the same laptop at work do the same. I believe it's because when using the nvidia gpu the temperature rises and the laptop throttles
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msantos avatar
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msantos
That the laptop has a worse performance when using the nvidia gpu yes, it makes no sense. But from what I've seen online there is alot of people complaining about throttling issues in more recent lenovo thinkpad models (T480, T490 and T14), so I wouldn't be that suprise if thats the case.
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Nmath avatar
ng flag
Nmath
Still, no. If you have two people addressing envelopes, two will achieve more than one alone even if one (who is exponentially more productive at the task) has to slow down a bit because their hand is cramped. I don't think this question can be answered since the problems seem self inflicted and this is an [XY Problem](https://meta.stackexchange.com/a/66378) in that your solution can only have made the problem worse. I would suggest to try to solve the actual problem instead of trying to handle the fallout from an improper solution.
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Henry avatar Ubuntu
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Henry

I had the exact same tearing issues on a ThinkPad T530 with Ubuntu 22.04. I could solve it by going into the BIOS and disabling NVIDIA Optimus. For me it was under "Config" -> "Graphics Mode". I set it to "Dedicated Graphics".

There was a description with the option and it said Optimus is only available for Windows Systems, so I figured it should be turned off for Ubuntu. Could also explain why you don't have the problem with Windows.

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