At first, I tried with Ubuntu Desktop LTS 18.04.3 but after grup, the screen is broken
since the latest Nvidia Geforce RTX 2070 Super is not detected and there is no proper driver installed.

And then, I tried with Ubuntu "Live" Server, and it fails in "probing the drive to install Ubuntu to".

The non-live version of Ubuntu Server ISO is working. It can be found in "alternate" installers page.

The same rufus is used to make a bootable USB stick.

With this server version, monitor, keyboard, and mouse can be detached, being a headless server.

$ sudo apt install openssh-server

The sshd service is enabled automatically. (ssh can also be installed during Ubuntu installation.)

But the GPU is not detected yet. It can be checked with "lshw".

But "sudo lshw -C display" still shows only "product: Nvidia Corporation".
$ sudo update-pciids
$ sudo update-usbids

Now the product name appears properly.

The driver should be installed now.

NOTE: "secure boot" is disabled in BIOS setting by removing PK (platform key).
Some says this contradicts with CUDA, which is not certain.
Anyway, secure boot makes problems in many cases.

To enable exFAT file system:
$ sudo apt install exfat-fuse exfat-utils

And then USB with exFAT file system can be connected.
$ sudo fdisk -l

Find the device and partition such as /dev/sda1
And then mount.
$ sudo mkdir /media/usb0
$ sudo mount -t exfat /dev/sda1 /media/usb0 -o uid=1000,gid=1000

Before reboot, or shutdown:
$ sudo umount /media/usb0