Multiple Displayport Displays: Slow Boot, Flickering

Hi!

I recently upgraded my system from F32 to F33, and I’ve been having some strange issues with my displays since the upgrade. I’m not sure if these are related, so I’ll try to present each independently.

Slow Boot
When I have 2 DisplayPort displays connected, Fedora takes an extra 30-60 seconds to boot, and it doesn’t follow the normal UEFI Splash -> grub -> Fedora Splash -> Gnome order. After grub, I get dumped to a grey screen with 3 dots near the bottom, then to a blank black screen with a frozen mouse pointer, then finally the Gnome login screen. I’ve tried unplugging one display, and boot returns to normal. I also did not have this problem when I used 1x DP and 1xHDMI display.

Interestingly, logging out also causes the black screen with the frozen mouse pointer.

Flickering
Once I boot up and log in, I see flickering on the display when I interact with the computer. Moving the mouse, moving windows, typing in the terminal, etc all cause the flickering to appear. If I open Settings and change any display setting (i.e., refresh rate), the flicker goes away and stays gone until I reboot again. I don’t even have to keep the change - I’ve been dropping the refresh rate from 75 to 60Hz, then cancelling the change.

I’m not sure what software/hardware is relevant to this, so I’ll do my best. I’m happy to provide more details as well.
Fedora 33 (upgraded from F32 without a reinstall)
Kernel: 5.8.16-300.fc33.x86_64, 5.8.17-300.fc33.x86_64
Gnome 3.38.1 on Wayland (Xorg experiences the same issue)
I’ve added “amdgpu.ppfeaturemask=0xffffffff” to my kernel parameters.
Ryzen 7 3700x
AMD 5700xt
1x Dell S2719DGF, DisplayPort
1x AOC Q27V3, DisplayPort

It may be that your video card does not have enough power to run 2 displays. It does not sound like software, but rather a power issue. That board is power hungry with a 225W rating. AMD also recommends a minimum of 600W PSU.

Thanks for the thought! I’ve had some trouble with this card related to power, but I’ve since moved to a 750W supply and those issues went away. I also don’t think this is the issue because I can make the flickering go away by changing a display setting (any setting) and reverting it, so the system is clearly capable of driving 2x QHD displays.

I did some more testing, I moved the AOC display to HDMI, and I still see the same issues, so perhaps DP isn’t relevant to the issue at all.