I attempted to install CUDA 10 on Ubuntu 18.04 using the official Nvidia repository. This downgraded the nvidia driver version to 418. After rebooting I only got a black screen, and I had to purge the repository and re-install nvidia-driver-435 in order to get a working display again.
The following errors were printed on dmesg:
Sep 11 21:27:39 al-desktop kernel: [ 800.054852] NVRM: RmInitAdapter failed! (0x26:0x65:1106)
Sep 11 21:27:39 al-desktop kernel: [ 800.054921] NVRM: rm_init_adapter failed for device bearing minor number 0
This error was repeated over and over until I purged the 418 driver.
Does this driver version even support my 2070 super?
ppa is not the official NVIDIA repository, nor is it maintained by NVIDIA
To keep your nvidia-driver-435 that you installed from ppa, then install the NVIDIA CUDA toolkit while deselecting the driver install.
For a runfile installer, you are prompted as to whether or not you want to install the driver, deselect the option. For a package manager/deb install, install the cuda-toolkit package instead of the cuda package.
If you install 10.1U2, i.e. 10.1.243, I believe the bundled 418.87 driver is compatible with the Super cards, but I haven’t double checked that. The drivers bundled with previous cuda toolkits are not compatible with the super cards. However the above method I describe can be used to keep your existing driver, as I’ve already mentioned.