|Should really add a third monitor, two doesn't cut it anymore.|
"dpm" support, must be selected at boot (via radeon.dpm=1) and is only supported on R6xx and newer asics.Which then suggested the following modifications
Upon doing these changes followed by a reboot it didn't work. The funny thing was I remember a few years ago someone else had this exact same problem, who suggested after the reboot, save the session, log out, then log in.
To test this when the grub menu appears press e (for edit) then replace the nomodeset (if there) with radeon=dpm=1. Press f10 to boot this session with the change.
Of course to make the change stick you must edit, as root, /etc/default/grub and change the
GRUB_CMDLINE_LINUX_DEFAULT= line to include radeon.dpm=1
eg GRUB_CMDLINE_LINUX_DEFAULT="radeon.dpm=1 quiet splash"
Then run sudo update-grub.
It worked, both monitors fired up with Linux Mint logo shown on each. Going through the monitor settings each monitor was identified correctly.
Here's the problem:
It's not a permanent solution, if the computer reboots/shutsdown for any reason, you lose the dual monitor display once again, unless you log out, log in again. A minor inconvenience but knowing it's a temporary solution just doesn't sit right with me.
Now from that Forum post it referred to the Radeon website where he found the solution. This suggests to me that this particular Linux Mint distribution didn't compensate for this particular problem on its release for this grapics card. I really don't have a problem with this because with each release there is bound to be bugs/errors. Creating a Linux distribution is huge and involves a lot of time and people, it's just that waiting for the next upgrade can take months.
Post from the Linux Mint Forums
Mentioned Radeon Link
In the mean time, I'm looking at trying a different distribution called MX Linux, there has been some good reviews on YouTube about this. Check out their homepage: https://mxlinux.org/.