[SOLVED] Screen flashing black randomly, more so on high refresh rates

TypicalHog · 2023-07-19 20:52:57

Hi

I'm a noob who has just installed Arch, but top quarter/third of my screen is flashing black for several milliseconds every few minutes on 1440p @ 59.95 Hz and it's driving me nuts.
I tried to search online for the solution, but the only thing I really came across are people saying NVIDIA driver is broken.
On 1440p @ 120/144 Hz, it's happening more often.
On 1440p @ 239.96 Hz, it's turning fully off for a few seconds about once every 20 seconds or so, sometimes more frequently.
On 1080p @ 239.96 Hz it's flashing black similar to 1440p @ 144 Hz.

The same thing has been happening yesterday on with KDE and using both Wayland and X11. (using Xfce4 now)
Bare metal installed Windows 10 works without any issues on 1440p @ 240 Hz.

Monitor: Odyssey G7 LC27G75TQSRXEN
Firmware: M-TG700CCAA-1016.1
DP 1.4 2560x1440 88.9 kHz 60 Hz / 358.1 kHz 240 Hz

neofetch
https://pastebin.com/yakBPVCL

nvidia-smi
https://pastebin.com/QteTEv2r

xrandr
https://pastebin.com/14fFea29

xrandr --verbose
https://pastebin.com/fvGmSh9R

Some commands I tried running, but the last one fails
https://pastebin.com/Ceb3m6zc

SOLUTION:
Forcing full composition pipeline and setting PowerMizer to "Prefer Maximum Performance" (this part possibly not relevant).

Last edited by TypicalHog (2023-07-26 21:25:53)

seth · 2023-07-19 21:34:00

Rather

# 2560x1440 @ 240.000 Hz Reduced Blank (CVT) field rate 240.000 Hz; hsync: 388.560 kHz; pclk: 1025.80 MHz
Modeline "2560x1440_240.00_rb2"  1025.80  2560 2568 2600 2640  1440 1605 1613 1619 +hsync -vsync

You'll need

Option "ModeValidation" "AllowNonEdidModes"

for either.

However while the EDID suggests aggressive modelines for 144/240,

  2560x1440 (0x1c0) 241.500MHz +HSync -VSync +preferred
        h: width  2560 start 2608 end 2640 total 2720 skew    0 clock  88.79KHz
        v: height 1440 start 1443 end 1448 total 1481           clock  59.95Hz

is just the regular CVT reduced blanking mode

The symptoms sound like a weak signal, though.
For an out of the box idea, disable wifi/bluetooth…

Bare metal installed Windows 10 works without any issues on 1440p @ 240 Hz.

Does the monitor OSD reveal what mode windows feeds it?
Ceterum censeo: 3rd link below.

TypicalHog · 2023-07-19 22:17:32

Does the monitor OSD reveal what mode windows feeds it?

Indeed.
2560x1440 352.8 kHz 240 Hz as opposed to 358.1 kHz.

The symptoms sound like a weak signal, though.
For an out of the box idea, disable wifi/bluetooth…

No WiFi or Bluetooth adapters. Using Ethernet. WiFi is in the house tho.

Ceterum censeo: 3rd link below.

Thank you! I completely forgot to do it even tho it almost caused me complete data loss once.
I really hate this garbage spyware OS, but I do like playing many games that have an anti cheat that doesn't allow Linux or Windows 10 VM.

# 2560x1440 @ 240.000 Hz Reduced Blank (CVT) field rate 240.000 Hz; hsync: 388.560 kHz; pclk: 1025.80 MHz
Modeline "2560x1440_240.00_rb2" 1025.80 2560 2568 2600 2640 1440 1605 1613 1619 +hsync -vsync

So... I guess I'll give this a shot, thank you!

Last edited by TypicalHog (2023-07-19 22:18:57)

seth · 2023-07-19 22:41:34

352.8 kHz < 358.1 kHz < 388.560 kHz

Monitor ranges (GTF): 50-240 Hz V, 30-358 kHz H, max dotclock 980 MHz

What means the cvt12 reduced blanking modeline won't work.
Don't try.

Edit: Check whether VRR is enabled, https://wiki.archlinux.org/title/Variab … _on_NVIDIA

Last edited by seth (2023-07-19 22:44:38)

TypicalHog · 2023-07-19 23:00:47

seth wrote:

352.8 kHz < 358.1 kHz < 388.560 kHz
Monitor ranges (GTF): 50-240 Hz V, 30-358 kHz H, max dotclock 980 MHz
What means the cvt12 reduced blanking modeline won't work.
Don't try.
Edit: Check whether VRR is enabled, https://wiki.archlinux.org/title/Variab … _on_NVIDIA

VRR doesn't seem to be on.

seth · 2023-07-20 06:15:46

What if you enable it?

TypicalHog · 2023-07-20 13:48:24

seth wrote:

What if you enable it?

I turned G-SYNC on and it's still happening. It was fine for a few minutes and then it turned on and off like 3 times in the span of like 10 seconds.
Is there a way to make it use same CVTs that work on Windows 10?

Last edited by TypicalHog (2023-07-20 13:53:08)

seth · 2023-07-20 15:36:40

You'd somehow need to extract the modeline, there used to be tools for older windows versions but I'm not aware of anything that does this for 8/10/11
To be sure: the OSD reports a different hfreq on linux (the expectable 358.1 kHz ?)

Modeline "2560x1440_240" 931.392 2560 2568 2600 2640 1440 ???? ???? 1470 +HSync -VSync

You need to guess the numbers for ???? - they're between 1440 and 1470, from the EDID and cvt12 heavily biases the front porch (so more like "1456 1464") while the naive and cvt1 modelines bias the back porch (1443 1453) and the edid suggests "1443 1448" (but has a vtotal of 1490)

The bulk of this is because the horizontal timings use cvt12 while the EDID has the cvt1 timings (and is more aggerssive on the vertical ones)
And you're driving the monitor outside it's own specs and all standards, so if you can, you want the see the actual windows modeline/timings

Also despite the overaggressive 240Hz mode, I doubt anything like this is going on w/ 60Hz?
Does the monitor report the same mode for windows and linux there?

TypicalHog · 2023-07-24 21:53:09

seth wrote:

To be sure: the OSD reports a different hfreq on linux (the expectable 358.1 kHz ?)

On Linux, it's reporting 358.1 kHz.
On Windows it WAS reporting 352.8 kHz until I changed the resolution to 1080p 60 Hz and then back to 1440p 240Hz, and since then - it has been 358.1 or 358.2 kHz and now I'm really confused as to what happened there.
Even though now it's reporting the same hfreq as Linux, there don't seem to be any issues on Windows.
Do you think this means something else might be at play?

seth wrote:

Also despite the overaggressive 240Hz mode, I doubt anything like this is going on w/ 60Hz?
Does the monitor report the same mode for windows and linux there?

On Windows, at 1440p 60 Hz, it's reporting 88.9 kHz (same as Linux).
While 240 Hz might be considered "overaggressive", I can see a clear difference between 144 Hz and 240 Hz.
I would even be fine with 120 Hz if I got it to work without issues, but 60 Hz is just soo choppy.

I found out how to add custom resolutions in Windows using the Nvidia control panel.
The first image is showing "automatic" timings.
The second image is showing the automatic timings with the total vpixels changed to 1470. (Some other changes might also be needed to make it work, but this value is giving me the same hfreq that monitor was reporting on the OSD earlier so I thought it may be of interest)
CVT1 CVT2

I have no idea what I should do with this info and would really appreciate your help.

EDIT:
Also, I can't test the above custom timing on Windows I think, it says 1440p 240 Hz resolution already exists. (Doesn't seem like I can edit or remove the existing one either)
I think I figured out how to get the above data into modelines I need for Linux, so I might try that.

Last edited by TypicalHog (2023-07-24 22:22:40)

seth · 2023-07-25 06:47:31

While 240 Hz might be considered "overaggressive", I can see a clear difference between 144 Hz and 240 Hz.

No you can't - you can sport artifacts to a greater degree but you're not processing visual information at any of those rates.
However, I meant the modeline for 240Hz that the output advertises is very aggressive in its timings (to keep the pclk down)

Let's say it's not the modeline, not the cable, not the monitor:
In nvidia-settings, enter the PowerMizer tab and select "Prefer Maximum Performance".
Does the flicker go away?

TypicalHog · 2023-07-25 12:33:51

seth wrote:

No you can't - you can sport artifacts to a greater degree but you're not processing visual information at any of those rates.
However, I meant the modeline for 240Hz that the output advertises is very aggressive in its timings (to keep the pclk down)

With all due respect, I ABSOLUTELY can, and by a long shot. I did an experiment once where my friend would randomly set the monitor to 144 Hz or 240 Hz and I got it right 10/10 times, and I didn't even have to wait for any artifacts to appear (no idea which artifacts you mean) or anything like that.
I was able to tell which refresh rate it was set to in under a second of moving the mouse cursor. To me at least, the difference is as clear as day.
I know my brain is not processing every single frame, not even at 144 Hz, but there is still something that's making the visual output WAY smoother.

seth wrote:

In nvidia-settings, enter the PowerMizer tab and select "Prefer Maximum Performance".
Does the flicker go away?

Even though they *seem* to be rarer (I can't say for certain, but it surely feels like it), my monitor still turned off 2 times in the last 15ish minutes on 240 Hz with "Prefer Maximum Performance" option.
i'll keep it that way, but the issue is still not fully solved. I might go to 120 Hz, then it will surely not turn off.

Thank you for the help, I can live with this if a fully solution can't be achieved.

seth · 2023-07-25 14:38:02

With all due respect

You're not a bird, I'm tired of this debate, but you're always seeing artifacts because the source renders slow and the increased frequency approximates "freesync" (or rather "is the technical base for it)
If you sync and the source renders at 59fps you cannot display at 60Hz but have to skip a frame for 30Hz, next frame is 60Hz again etcetc. That's what you see and that's what's greatly diminished by higher refresh rates because now you've a frame every 7ms instead of 16.6 what brings you up to 42Hz for the odd frame.
Everything else is delusion to justify your investment
(The mouse cursor is biased because you're moving it and either you're moving it fast and it'll skip pixels anyway or you moving it slow at which point your hand isn't able to maintain a constant motion by any chance, it's not a good test at all)

Back on topic:

I might go to 120 Hz, then it will surely not turn off.

Did you test this?
Please post your xorg log and see https://wiki.archlinux.org/title/NVIDIA … en_tearing
A lot on that page ish shocking nonsense, but you might be happy about TripleBuffering (introduces 1fps lag but mitigates the vsync-of-slow-source issue as well) and notably "ForceFullCompositionPipeline" keeps the GPU busy w/o moving it to full performance (you might get away w/ that)

The file should look more like

Section "Device"
        Identifier "NVIDIA Card"
        Driver     "nvidia"
        Option         "ForceFullCompositionPipeline" "on"
        Option         "TripleBuffer" "on" # optional
EndSection

and the two options should then show up in your xorg log.
For a quick test you could also just "xrandr --output DP-2 --scale 1.1" which will scale your output by 10% but more importantly trigger the full composition pipeline (which afaiu is also active for multiscreen setups anyway)

TypicalHog · 2023-07-26 21:19:10

seth wrote:

You're not a bird, I'm tired of this debate, but you're always seeing artifacts because the source renders slow and the increased frequency approximates "freesync" (or rather "is the technical base for it)
If you sync and the source renders at 59fps you cannot display at 60Hz but have to skip a frame for 30Hz, next frame is 60Hz again etcetc. That's what you see and that's what's greatly diminished by higher refresh rates because now you've a frame every 7ms instead of 16.6 what brings you up to 42Hz for the odd frame.
Everything else is delusion to justify your investment
(The mouse cursor is biased because you're moving it and either you're moving it fast and it'll skip pixels anyway or you moving it slow at which point your hand isn't able to maintain a constant motion by any chance, it's not a good test at all)

Correct me if I'm wrong, but what you described would happen about once per second (the skipped frame).
But I can tell the difference on any sub second interval, and continuously.
When I move my mouse left and right (or up and down, or any way really) on 144 Hz, I see about 7-9 mouse pointers at once, while on 240 Hz I see way more, I can't count them precisely, but there's at least like 12, which is expected since 144 / 240 = ~1.67 and 8 * 1.67 = ~13
I believe this is because of ghosting (each mouse pointer stays rendered on the screen for awhile). Is that an artifact? Sure... But it is def making everything so much smoother and there is unarguably more information on the 240 Hz screen.
Also, V-Sync in CS:GO would make my brain hurt. I once turned it on by accident when I was messing in the settings and I INSTANTLY felt it. I could feel the input lag and it was agonizing. (There are certain games where I prefer it to tearing tho)

I have forced full composition pipeline and I haven't seen a single flicker or blank on 240 Hz since (it's been like an hour).
I consider this solved, but will update if I notice any issues still being there.

Thank you so much!
Any way I can send you a tip? You've helped me a lot and I've learned stuff I didn't know before.

Last edited by TypicalHog (2023-07-26 21:38:32)

Arch Linux

#1 2023-07-19 20:52:57

[SOLVED] Screen flashing black randomly, more so on high refresh rates

#2 2023-07-19 21:34:00

Re: [SOLVED] Screen flashing black randomly, more so on high refresh rates

#3 2023-07-19 22:17:32

Re: [SOLVED] Screen flashing black randomly, more so on high refresh rates

#4 2023-07-19 22:41:34

Re: [SOLVED] Screen flashing black randomly, more so on high refresh rates

#5 2023-07-19 23:00:47

Re: [SOLVED] Screen flashing black randomly, more so on high refresh rates

#6 2023-07-20 06:15:46

Re: [SOLVED] Screen flashing black randomly, more so on high refresh rates

#7 2023-07-20 13:48:24

Re: [SOLVED] Screen flashing black randomly, more so on high refresh rates

#8 2023-07-20 15:36:40

Re: [SOLVED] Screen flashing black randomly, more so on high refresh rates

#9 2023-07-24 21:53:09

Re: [SOLVED] Screen flashing black randomly, more so on high refresh rates

#10 2023-07-25 06:47:31

Re: [SOLVED] Screen flashing black randomly, more so on high refresh rates

#11 2023-07-25 12:33:51

Re: [SOLVED] Screen flashing black randomly, more so on high refresh rates

#12 2023-07-25 14:38:02

Re: [SOLVED] Screen flashing black randomly, more so on high refresh rates

#13 2023-07-26 21:19:10

Re: [SOLVED] Screen flashing black randomly, more so on high refresh rates

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