Random flashing pixels, only if bgcolor is a certain shade of gray

[Red Squirrel]

I have this weird issue where I get random pixels that flash but only if the background is a certain dark shade of gray. I have confirmed it only does in on my Linux machine, if I switch to another machine even showing same colours it does not do it. So I at least ruled out the monitor thankfully. Paid like over $500 for it only a year ago so almost had a mini heart attack thinking something was wrong with it. The only way to solve it is to set refresh rate really low like 30 but that makes doing anything quite brutal, especially watching video as it's like a slide show. Turning it down to 50 makes it somewhat tolerable but I still get the flashing dots just not as much. For a while I was able to get away with both monitors at 60 but for some reason the problem came back now. Anyone ever see this before?

I'm suspecting it's some weird driver issue. I also tried rebooting. It went away then slowly started to come back.

Added video to show what I mean:

https://www.youtube.com/watch?v=---dY0usoe4

When it goes black it's because I'm switching to the other machine just to show that it does not happen to that one. Both are on same site.

Here's some info that might help:

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Screen 0: minimum 320 x 200, current 3840 x 4320, maximum 16384 x 16384
DisplayPort-0 disconnected (normal left inverted right x axis y axis)
DisplayPort-1 disconnected (normal left inverted right x axis y axis)
HDMI-A-0 connected primary 3840x2160+0+2160 (normal left inverted right x axis y axis) 621mm x 341mm
   3840x2160     60.00 +  60.00    50.00*   59.94    30.00    25.00    24.00    29.97    23.98  
   2560x1440     59.95  
   1920x1200     60.00  
   1920x1080     60.00    50.00    59.94    24.00    23.98  
   1600x1200     60.00  
   1680x1050     59.88  
   1280x1024     60.02  
   1440x900      59.90  
   1280x960      60.00  
   1280x800      59.91  
   1280x720      60.00    50.00    59.94  
   1440x576      50.00  
   1024x768      60.00  
   1440x480      60.00    59.94  
   800x600       60.32    56.25  
   720x576       50.00  
   720x480       60.00    59.94  
   640x480       60.00    59.94  
HDMI-A-1 connected 3840x2160+0+0 (normal left inverted right x axis y axis) 621mm x 341mm
   3840x2160     60.00 +  60.00    50.00*   59.94    30.00    25.00    24.00    29.97    23.98  
   2560x1440     59.95  
   1920x1200     60.00  
   1920x1080     60.00    50.00    59.94    24.00    23.98  
   1600x1200     60.00  
   1680x1050     59.88  
   1280x1024     60.02  
   1440x900      59.90  
   1280x960      60.00  
   1280x800      59.91  
   1280x720      60.00    50.00    59.94  
   1440x576      50.00  
   1024x768      60.00  
   1440x480      60.00    59.94  
   800x600       60.32    56.25  
   720x576       50.00  
   720x480       60.00    59.94  
   640x480       60.00    59.94  
DVI-D-0 disconnected (normal left inverted right x axis y axis)

Code: Select all

System:
  Kernel: 5.11.0-37-generic x86_64 bits: 64 compiler: N/A 
  Desktop: Cinnamon 4.8.6 wm: muffin 4.8.1 dm: LightDM 1.30.0 
  Distro: Linux Mint 20.1 Ulyssa base: Ubuntu 20.04 focal 
Machine:
  Type: Desktop Mobo: ASUSTeK model: PRIME B350-PLUS v: Rev X.0x 
  serial: <filter> UEFI: American Megatrends v: 5407 date: 12/31/2019 
CPU:
  Topology: Quad Core model: AMD Ryzen 3 1300X bits: 64 type: MCP arch: Zen 
  rev: 1 L2 cache: 2048 KiB 
  flags: avx avx2 lm nx pae sse sse2 sse3 sse4_1 sse4_2 sse4a ssse3 svm 
  bogomips: 27946 
  Speed: 1546 MHz min/max: 1550/3500 MHz boost: enabled Core speeds (MHz): 
  1: 1547 2: 1547 3: 1551 4: 1551 
Graphics:
  Device-1: AMD Ellesmere [Radeon RX 470/480/570/570X/580/580X/590] 
  vendor: Micro-Star MSI driver: amdgpu v: kernel bus ID: 07:00.0 
  chip ID: 1002:67df 
  Display: x11 server: X.Org 1.20.11 driver: amdgpu,ati 
  unloaded: fbdev,modesetting,vesa tty: N/A 
  OpenGL: renderer: Radeon RX 580 Series (POLARIS10 DRM 3.40.0 
  5.11.0-37-generic LLVM 12.0.0) 
  v: 4.6 Mesa 21.0.3 direct render: Yes 
Audio:
  Device-1: AMD Ellesmere HDMI Audio [Radeon RX 470/480 / 570/580/590] 
  vendor: Micro-Star MSI driver: snd_hda_intel v: kernel bus ID: 07:00.1 
  chip ID: 1002:aaf0 
  Device-2: AMD Family 17h HD Audio vendor: ASUSTeK driver: snd_hda_intel 
  v: kernel bus ID: 09:00.3 chip ID: 1022:1457 
  Sound Server: ALSA v: k5.11.0-37-generic 
Network:
  Device-1: Realtek RTL8111/8168/8411 PCI Express Gigabit Ethernet 
  vendor: ASUSTeK driver: r8169 v: kernel port: f000 bus ID: 03:00.0 
  chip ID: 10ec:8168 
  IF: enp3s0 state: up speed: 1000 Mbps duplex: full mac: <filter> 
Drives:
  Local Storage: total: 342.81 GiB used: 214.73 GiB (62.6%) 
  ID-1: /dev/sda vendor: Crucial model: M4-CT128M4SSD2 size: 119.24 GiB 
  speed: 6.0 Gb/s serial: <filter> rev: 0309 scheme: GPT 
  ID-2: /dev/sdb vendor: Kingston model: SA400S37240G size: 223.57 GiB 
  speed: 6.0 Gb/s serial: <filter> rev: 71E0 scheme: GPT 
Partition:
  ID-1: / size: 116.38 GiB used: 19.92 GiB (17.1%) fs: ext4 dev: /dev/sda2 
Sensors:
  System Temperatures: cpu: 30.6 C mobo: N/A gpu: amdgpu temp: 55 C 
  Fan Speeds (RPM): N/A gpu: amdgpu fan: 1103 
Repos:
  No active apt repos in: /etc/apt/sources.list 
  Active apt repos in: /etc/apt/sources.list.d/audio-recorder-ppa-focal.list 
  1: deb http://ppa.launchpad.net/audio-recorder/ppa/ubuntu focal main
  Active apt repos in: /etc/apt/sources.list.d/official-package-repositories.list 
  1: deb http://packages.linuxmint.com ulyssa main upstream import backport #id:linuxmint_main
  2: deb http://archive.ubuntu.com/ubuntu focal main restricted universe multiverse
  3: deb http://archive.ubuntu.com/ubuntu focal-updates main restricted universe multiverse
  4: deb http://archive.ubuntu.com/ubuntu focal-backports main restricted universe multiverse
  5: deb http://security.ubuntu.com/ubuntu/ focal-security main restricted universe multiverse
  6: deb http://archive.canonical.com/ubuntu/ focal partner
Info:
  Processes: 254 Uptime: 1h 42m Memory: 15.57 GiB used: 4.00 GiB (25.7%) 
  Init: systemd v: 245 runlevel: 5 Compilers: gcc: 9.3.0 alt: 8/9 
  Shell: bash v: 5.0.17 running in: gnome-terminal inxi: 3.0.38 

[SMG]

So I at least ruled out the monitor thankfully.

I would guess there may be some cable differences. Have you been able to do a test to rule out the cable?

You indicated a restart cleared it for a while. Might there be a relation to the GPU's temperature and when this happens?

[Red Squirrel]

Going to be tough to test that since everything is cable managed and PC is actually in another room, but I'll see what I can do to rule it out.

GPU temp seems to be fine.

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amdgpu-pci-0700
Adapter: PCI adapter
vddgfx:        1.08 V  
fan1:         856 RPM  (min =    0 RPM, max = 4500 RPM)
edge:         +54.0°C  (crit = +94.0°C, hyst = -273.1°C)
power1:       33.04 W  (cap = 135.00 W)

k10temp-pci-00c3
Adapter: PCI adapter
Tctl:         +30.1°C  
Tdie:         +30.1°C  

I set refresh rate back to 60 so I can see if it's doing it to both monitors or not but now it's not doing it at all, seems very intermittent. Was working from home when I originally made the post so could only see primary as other was set to my work stuff.

[Red Squirrel]

I have everything set to 60hz on both monitors and this seems to have randomly gone away on it's own... very weird. But if it happens again I try to see if I can swap the cables at the PCs, probably the easiest way to test without having to completely recable everything.