Yeah.... I tried that, its not working, seems like Manjaro just doesn't work with NVIDIA 2080tis
maybe next drivers nvidia can change this
have you tried this ?
Which drivers introduced support for the 2080ti?
If there isn't an installer image which includes appropriate drivers then the hardware won't work and you'll have to wait.
The other factor is that you have two cards. Are these set up in SLI or with NVLink or anything similar? Have you tried with having only one of them installed at a time?
Have you tried any other distros? If not then this isn't necessarily a "Manjaro" issue but a "Linux" issue.