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Screen flickering on dual monitor

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Hey @Edhawk , so sorry for the late reply, been very busy lately with other stuff. Here are my answers to your questions ( as my issue still stands ):

Q: "You have tried a different HDMI cable when connecting the Lenovo display? Do you see the same flickering issues?"
A: No, I'm 100% sure is not the cable because the issue manifested itself before I even used an HDMI monitor.

Q: "The flickering only happens with macOS, i.e. if you use the same dGPU and cable with either a Linux distro or Windows you do not see the same flickering?"
A: I only have MacOS installed on this system ( is my main working computer ) so I can't give you a correct answer. Even if I'd attached a new drive with different OS I couldn't use it long enough to test it. As I just said, is my day by day working computer and MacOS is a must.

Q: "Which version of macOS are you running?"
A: 10.15.7 (19H524)

Q: "Have you tried running the system without WhateverGreen.kext (WEG)? I ask this as one of my systems with an Nvidia Quadro K4200 dGPU behaves poorly when using WEG. Works perfectly without WEG."
A: Yes, I only added WEG a few days ago trying to make the audio hdmi work ( no success though ).

Q: "Do you have your Intel iGPU, assumed HD 4600, set to run 'Headless' or can you see details for the IGPU in the System Information > Graphics/Display report?"
A: The IGPU is not in my graphic/display report. I do not know where to set it to run "headless" ( in BIOS maybe!? )

Q: "With the IGPU fully enabled, does the flickering occur when you connect the two screens to your motherboard HDMI and DVI ports?"
A: I haven't tested the MB hdmi and dvi ports as I saw that pointless while having the nvidia gtx 650 ti card. But will do.

Hope these will give you an idea about what could be wrong. Thanks!
 
Unfortunately no they don't, because you couldn't answer all the questions.

I understand the issue about this being your main work system, and your reluctance to mess around with it as it might mess up your ability to work.

This may be because the GTX 650 Ti uses a GK106 core. While it is a Kepler GPU and a lot of these cards are still natively supported in macOS, the cards with the GK106 core have always been flaky, due to a memory leak on these GK106 chips.

From what I understand the memory leak issues are part of the reason Apple and Nvidia fell out. As Apple wanted the drivers released under an open licence, so they could fix the issue and Nvidia wanted to keep the drivers proprietary and only within their domain.

What reminded me of this issue is re-reading this post from the beginning, you said the graphical artefacts have been present from when you first used the Nvidia GTX 650 Ti. I have a couple of GTX 660's that suffer with the same graphical issues. Like you, the artefacts didn't appear all the time but sufficiently frequently to be a pain. Using the NVIDIA Web Drivers didn't help either.

As this is your main work system I think you would be better served replacing the GTX 650 Ti with a macOS compatible AMD GPU. A second-hand RX 580 or similar would probably be ideal.

On another matter using HDMI with macOS can frequently be problematic. If possible I always opt for DisplayPort, as Apple use that type of connector (Mini DisplayPort (mDP) in their older systems and Thunderbolt in the newer ones). If that isn't possible I then look for a DVI connector. Only if neither a DP or DVI connector are available would I think about using a HDMI connection, as Apple don't use the HDMI connector on any of their systems. Same goes for VGA connectors.

So if in the future you are looking to upgrade or replace a display monitor or GPU, think about the connection options alongside the resolution etc.
 
Alright then, this at least gave me a hint on where the issue is. On both my problems, with the display and with the audio. The bottleneck seems to be the graphic card so that will be the next on my shopping list. The monitor does have a display port but the nvidia card doesn't. I just tried with both monitors on dvi ( card has 2 dvi ports and one hdmi ) and I still have no audio. I then disconnected both monitors and tried with the one with the speakers sequentially in all of the 3 ports ( 2 dvi and 1 hdmi ) and none of them provided audio output. So I give up on that one as is not essential.
Thank you very much for the time and info provided!
 
Just for some clarity on the GK106 core issue, the screenshot below is from the legacy Nvidia section of the GPU Buyers Guide - https://dortania.github.io/GPU-Buyers-Guide/

Screenshot 2021-02-24 at 22.18.51.png

This lists the common GK106 core Kepler cards, all of which suffer with the Graphics artefacts issue.
 
Edhawk said:
Just for some clarity on the GK106 core issue, the screenshot below is from the legacy Nvidia section of the GPU Buyers Guide - https://dortania.github.io/GPU-Buyers-Guide/

View attachment 510433

This lists the common GK106 core Kepler cards, all of which suffer with the Graphics artefacts issue.
Click to expand...
It's crystal clear now where the problem is! Thanks a lot, you've been very helpful!

Quick question: does it seem logic to you that a simple logout from the os while the artefacts are manifesting is fixing the issue? Because it so looks like a driver reload... And the logout does fix the issue, until next time though.
 
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That may be the case, but you are the first person I have heard report this 'fix'.

I am not sure how a restart would fix the memory leak, but if it works for you great.
 
Not sure if it has any meaning, but I don't have to restart the OS, just a user logout and is all fixed.
 
To be honest that makes even less sense to me than a warm reboot fixing the issue. At least with a reboot you would see the drivers etc. being reloaded. I wouldn't have thought Signing Out of your account would have the same impact. But like I said, if it works all to the good.
 
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