Set Up Raspberry Pi 4 (B) with Ubuntu Server 20.04 (+Minimal Desktop) and Argon One Fan Control

*updated 2020 Oct 21, change the method to obtaining desktop GUI and adding some troubleshooting

In this tutorial, I will write about how to set complete Ubuntu server 20.04 into Raspberry Pi 4 (B) including the desktop GUI. Note that mine is 8GB version, so I use Ubuntu 64-bit for that. It may works with 32-bit or 64-bit/Pi 3 pairs. I also use Argon One case with fan control. There will be slight workaround than what is written in Argon One instruction manual.