Question Sudden framerate drops when I extend desktop (or when there's another cable connected)

Apr 19, 2022
So I have an AMD GPU since end of last year. Performance is good, it is working well (it is a second model, first one was faulty, 6900 XT Red devil ultimate). My issue is the following:
- there are random performance (framerate) drops at ever 10-20 sec when I extend the desktop to a secondary monitor (it is random because somehow it's not always present, but more times than not)
- when a secondary monitor DP or HDMI cable is connected (but not extended on that device)

What can cause this issue and how to solve it? I have latest drivers, it always persisted on this GPU somehow (under win 11). Cables are OK I think, but wasn't able to check them individually (as they are kinda long). When I switch to TV for example there are no issues, but if I switch back to desktop (monitor) on primary then sometimes there are these fps drops (in these cases the GPU efficiency also drops to close to zero). I don't go black screen however. Is win11/radeon checking up with other devices even if they are not being used, just connected? My previous GPU (2080S) never did anything quite like this, ever. However when I used the TV on HDMI it often got black screen or screen was pixelated and faulty. Could it be that this VGA does different errors with a faulty cable than the other and that the error here is being present in the form of framerate drops? (I don't get a "device connected/disconnected" sound or stuff like that)

Any ideas? It makes streaming and multi-display work really difficult for obvious reasons.