I've had my 2080ti since about april now, and for the most part its been fine. I got more fps than what i would with a 1050ti and was pretty happy with it, haven't tried playing gta till 2 nights ago, and since then my experience has been horrible. I can't reach 100fps no matter what settings or res. I play 1080p which I know is what the 2080TI is not intended for. I'm planning on getting a 1440p monitor soon, but until then I use a custom 2650x1440 resolution in the nvidia control panel, and it works perfectly (boosted my Fortnite fps from 70 on low settings to 380 on low) and it works fine with other games, I tried that with gta and nothing changed, I tried dsr X4 on 1080p and nothing changed and I can't see the problem. It may be my ram as a stick got damaged and no longer works so I am left with 8GB, but even with 8GB my 1050ti gets more frames. any help would be appreciated.
I'll link a video soon of my settings and monitoring software, but I can confirm the GPU sits a around 40-50c and only 40% usage and the cpu around 50-60 at about 40-50 usage.
Specs:
MSI Trio RTX 2080TI
Intel I7-8700K - Kraken x62 water cooled
HyperX Fury 16gb - only 8gb working