Assistance in setting up Linux workstation

I have bought last year a computer, to combine with other parts that I already own, and was planning to install on it a Linux OS. New computer: - CPU: Intel Core i5 14600 - Motherboard: ASUS prime B760 plus - RAM: 16GB - SSD drive 512GB Pre-Own parts: - GPU: NVidia GTX 1080TI - HD drive 8TB - HD drive 2TB OS: Ubuntu 24.04.1 LTS Noble Numbat However I am not very well versed in sysadmin and didn't managed to build and install properly the system, and I have now the following issues: Main OS issues: - Only 1 out of my 2 screens is functioning. When I open the system app, I can see that my graphic card is marked as LLVMPipe. Which leds me to believe that my nvidia graphic card and/or driver is not properly installed - The SSD drive i understand is useful to speed up startup process. But it seems that the OS has not been properly install between it and my 8TB hardrive, as now i often receive alerts that it is almost full. My downloads end up by default on the SSD and i constantly need to copy paste them on the 8TB drive. - my second hardrive (2TB) does not seem to auto mount at start. It does show in the file explorer, however symlinks to it appear broken before i actually navigate to it using the file explorer - At start up, and after the system has booted, I see a screen that asked me to choose between various OSes (see photo) - this is because I used to have linux installed on some of those older hardrives - but I would like to streamline the boot and not have that screen now. I would also lke to solve in the same go the following minor software issue: - I have tried to install Obsidian but somehow i find it hard to install it properly. Now the only way it starts is by going to the command line and stating it with ./Obsidian --no-sandbox Lastly, and to keep in mind if the system needs to be reinstalled, I have a personal programming project that uses postgresql. It should be made sure that it still works.