My Gigabyte Gaming rtx 2080ti (arrived 10 days ago) started playing up today.
I applied the gigabyte bios update for the GPU on day 1, no problems until today.
Black screens started to appear in games, causing them to crash. Frequently the game audio could be heard still going on in the background. More often then not; task manager wasn't available to end task resulting in the need to hard reboot.
On occasions my machine would restart then at the windows login screen; black screen would occur followed by no signal messages (both screens).
Safe mode was accessible so I tried to revert the driver; to no avail.
Plugged my gtx 980ti back in, back in business.
Plugged rtx 2080ti back in, after reseating this appeared to work normally for 2 hours before black screens/hard resets.
I also had a GPU/ no signal crash using Excel!
Gamers Nexus has uploaded a video explaining that this appears to be widely reported on higher refresh rate monitors (G sync and non g sync) and multi monitor setups (I have both).
I updated my Aorus RGB software from v1.46 to v1.47 (now that I think of this I'm thinking this could be a likely contribute); I will uninstall this tomorrow and give it another try before RMA'ing.