I have been using my 7900xtx+7800x3d for 4 months now and still got the same issue. It drives me nuts.
Whenever I start my PC with both my monitors plugged in (240hz@1440p & 144hz@1080p), my second monitor stays on a black screen and my PC starts stuttering. Both monitors are connected with display port 1.4.
Whenever I plug the 2nd monitor in & out the issue persists. Windows display shows that both monitors are connected.
The only way it works is when I plug my 2nd monitor in after my PC is started, this is how I have been using it. It was working fine on my 5700xt+3600 so I can't pinpoint the root of this issue.
I tried AMD cleanup utility and DDU in safe mode for the GPU drivers.
Anybody that can help me out? I know I am not the only one with this issue because on Reddit people shared the same problem without a solution.
First thing i would try
I am not sure if this is a bios or if it is making it to windows and it is a windows/hardware issue
Swapped DP port order, noticed it only happens on 1 DP port. Tried different dp cables (including 1.4 for 240hz), firmware on monitor, clean windows boot, bios firmware update etc.
I have to believe the GPU is faulty, trying my luck with the support now. Thanks for the reply.