2080Ti black screen

[D.Wreck]

Hello great people of the internet I have been chasing down a problem with my 2080ti’s all year. It started when I water cooled my graphics cards I have 2 2080Ti cards I installed the EKWB water blocks on them my self with the help of a friend after installing the cards in the computer and going to boot up I came to the login screen and then black screened. Since then I have replaced motherboard,CPU,Ram and nothing seemed to fix the problem. I did get to the point where I can login to the computer and run a game but it plays like shit skipping around getting like 2 FPS, I have since then ran 3DMark test on the cards and the few times I have got them to finish a Time Spy without black screening. I have got a score of like 1,200 when I should be getting results in the area of 10,000. Today I installed my old 980Ti in the build and ran a time spy and got a result of 5,508 so at this point I am certain I have a graphics card issue. I have no clue where to go from here or what next to do please let me know if you have any advice for me. 

[bmx6454]

have you tried each card one at a time to rule out one of them being the issue?

[D.Wreck]

Yes I have tried both cards one at a time one of them seems to black screen more than the other but both are having issues and just can’t seem to handle the load of any game. I have watched YouTube and search the web all day long with both but when I try and run any game It seems to black screen or get terrible FPS even with graphics settings all the way on low.