Just had something of a shock a couple of days back, I was transferring some large and very critical
file on my 2nd rig (with the VEGA64 Red Devil aka my precious, and if you're wondering, my RX 6900 XT is the One), I'd thought I'd safely ejected one of my external HDD (though, thinking back, I'd noticed that there wasn't a sound/tone that usually accompanies a safely removed/ejected HDD/device).
Anyway, I unplugged the HDD which was attached to one of four USB3.0 ports up front and to my utter surprise, my monitor went off due to 'No Signal' being detected. Also, KB and mouse went off as well. So, okay, I simply have to restart and everything should be back to normal. Did that and zip, nada, my KB and mouse stayed off (no RGB) and my monitor stayed off as well.....had a sinking feeling I'd somehow killed my precious and quite possibly the USB ports as well. Tried restarting a couple more times, and my last attempt, my KB+mouse lit up, but the monitor stayed off...that sinking feeling got worse.
Took out my precious, and replaced it with my very ancient but still reliable PowerColor HD7970 and Lo, and behold! My rig started without issue, which only served to reinforced my belief that I'd kill my precious.
Anyway, this morning, somehow guided by the Force, I decided to pop in my precious back into my 2nd rig (had it in its box for a couple of days while I was using the HD7970) and at first, the monitor came on, then went off, repeatedly. I was using the HDMI port on the monitor because my HD7970 does not have DP.
Anyway, I attached my DP cable to the card and monitor and restarted and everything worked! Booted as normal to desktop and my precious performed as if nothing had happened! I guess I'm overjoyed, hence this rather long post. And to show that sometimes, hardware can behave rather strangely, and the solution can be found with the Force.