Hi. I am running into a bit of a weird problem related to HDMI vs DP auto-select for the card. Recently, I needed to change my output to HDMI due to monitor's only display port needed to be repurpose for something else. All is well as my monitor (acer xv282k) is 4k 144hz and HDMI2.1 compatible. But, when I restart the computer, after the windows 11 circle loading screen, I get stuck with a black screen. PC looks like it's asleep. Only when I press the power button twice (put it to sleep, then back) would the display show back up.
 
My theory is that because both 3090 and my monitor do auto detect which source is active. After windows screen, there's a long wait (fast boot off) before windows boots up. During this time, the monitor cycles to other sources thinking that HDMI is disconnected. There are visual evidence of this. And because the monitor got off the HDMI input 3090 is in, when windows is finally ready, it thinks that no input is connected hence going into this semi-sleep mode (case power button blinking similar to sleep). By the time the monitor cycles back to the original HDMI, PC already gave up outputting HDMI signal. 
 
I didn't see this behavior while using DP probably because DP either booted faster or it's the highest priority port for the 3090. I can confirm that by turning off auto detect on my monitor I can avoid this issue. However, I rely on this to switch between my devices. So is there a way for me to fix this on the PC / 3090 side to commit to HDMI output?

@methodical2 I would verify that the top most DP port works for you first. There are documentation of the priority of ports. If so, I think you are on the same boat as me with HDMI being a second class citizen leading to weird, intermittent issues. 
 

The monitor is currently connected one active host with other ports unplugged. After losing connection to the pc after the splash screen, This monitor naively cycles through all the ports once in order and then goes to sleep. No amount of tweaking from the monitor end could make the pc output signal from the hdmi port afterward. Only when I put the pc to sleep and then back would the pc try to output from the hdmi again (DP all unplugged). When that happens, the monitor wakes up and finds the pc’s hdmi signal quite quickly.

I could try to reproduce this with integrated graphics and see if it’s still an issue. However, since I can avoid this already by using DP to DP with the existing 3090 to monitor connection, it might not show anything new.

Cool GTX...Does the Monitor have a sleep mode you can disable, especially deep sleep which has a history of causing other issues?...

If this could be the case, then this sounds like it could be my monitor issue.  The LG OLED has a deep sleep mode that is activated.  I will disable and see what happens.
 

Cool GTX
 
 
One simple test - Clear your Windows Startup file, because Windows just keeps using the same (last successful) "startup file" by default.
 
How to Clear your Windows Startup file: 
--> Hold shift key down, select "power" then "Shut down" - Hold Shift key until all power is Off on the PC.  Now reboot
 
Does the Monitor have a sleep mode you can disable, especially deep sleep which has a history of causing other issues?
 
What happens when your "break the conventional wisdom" & turn the PC on First, wait a few seconds then turn on your monitor?

 
Thanks for the suggestion. 

Sadly this didn't change the behavior for me. I was able to confirm again by not auto-switching the source port on my monitor works fine using HDMI. So I still believe the root cause of the issue is the PC losing signal for too long. Or another way to put it, the monitor's wait time is too short before hopping channels. Unfortunately, the later I have no control over. 
 
For my use-case my monitor is always on and auto-wakes when new signal comes. I powercycled the monitor many times too but no change in this behavior. So the PC is always turned on second to wake the monitor. I tried to power on the monitor 5 seconds after the PC started booting. The monitor takes another 2-3 s to bootup. By that time, the PC is already on splash screen (no additional wait). But the same behavior persisted after splash screen as described previously. I tried again and waited > 1 minute post PC startup to power on the monitor. The monitor then proceeded to search every port for signal but couldn't find any before going to sleep. This I believe is the same as the default behavior where the PC gave up output on HDMI because it could not detect monitor connection while booting. 
 
I also tried enabling windows fast boot (default off). It didn't boot faster enough to make a difference either. 
 
 
Rest of my PC spec if it helps. 
Intel 12400
Asus B660i 
Windows 11 on PCIe gen 4 drive
 
EDIT: added minor details.

exe163
Small bump. Still having this issue and not sure what to do about it. 

If I understand you correctly, using 'auto detect' on your monitor is causing the issue.  The firmware has been updated since the monitor was released. Do you have the latest firmware for your monitor?  https://www.acer.com/us-e...o-kg2/pdp/UM.PX2AA.V01