Well, it does seem like the progression of the problem which led to no function at all in 3D suggests some kind of hardware degradation in my mind. Changing all the settings may just have been passing time for you while the inevitable result came to be. If that's the case, then nVidia should cover you for the hardware problem (is it FE, or a third party card?). I guess your only options are to wait for them to respond or start from scratch. If this is an upgrade, do you have your old card? You could try it again and see if your system is stable with the 2080 ti out of the picture. Then, swap the 2080 ti back in. Maybe before that I would double check all hardware related issues by pulling the card, making sure the slot is free of dust, reinstalling it, and repatching the power cables. If you had a bad connection somewhere, this could fix that kind of problem. How's your case's airflow? I'm wondering if there was a problem with thermals. Were you monitoring temps? 3d mark saves that info, so let us know what those temp graphs look like or post the images here if you can.