I have tried as many things as I could find through Google,Duck Duck LInux searches. I tried Arandr, Xrandr but keep getting display unknown
I changed windows manager, now back to a reset Compiz, changed and added displays to the general tab a couple of times. i used Mate tweaker to set and reset but continue to be unable to get the 2 displays I have identified. I had a 7950 3gb OC gpu and all was fine , the only hardware change was to get the RX480.
I have one DVI and one HDMI, both are new and work with the Windows side of the dual boot set up
I check the clocks since at one time i had a problem with the sys clocks going haywire after the 18 lts install
I have the HDMI through my Onkyo SR608 then to a LG42LD550 and dvi to samsung 2430 monitor.
I am not sure where to go. I tried so many things I cant remember. but from any combination of a 'display unknown' or unable to identify monitors , displays combined with linux, mint 18 and more i cant remember. I reinstalled the xserv amd drivers a couple of times to see whether that would stimulate the recognition
I never had this kind of trouble with Linux as far as monitor ID. all i get is one giant pink rectangle 1920x1080 _77 refresh rate .in the display manager. both monitors are working but as mirrors .
i do have 2 displays as output in compiz 690x480+0+0 came default and i added the 1920 setting though it wasnt necessary since the display manager
xrandr --display gives only one 1920x1080 with refresh rate and i forget the other number/data but not much. I tried to add but nothing took. and i forget the exact reason other than it failed
I am hoping that in my intensity to fix it on my own I've overlooked some simple thing.
I am learning some things but am still pretty new on this. Ive tried for a week without changes and rather than just avoid the Linux side of the machine, I posted this.
I have tried 2 kernel updates to see whether maybe my RX480 8gb wasnt in the prior kernel. no luck there.
I am at 4.4.53 , or 1 before the list goes to 4.8 but by the time Mint 18.1 upgrade came out I am certain the rx480 was around so was grasping at straws by this time
Thanks
John

i think you missed telling us about your actual problem (with code please), or maybe it got lost in your flood of words...

I put the issue right in the title and the rest was what i did already
I forgot you've already asked me to limit info when you helped on another graphics issue,driver then ,too, i think
Ive found out that the RX480 has known driver issues or properly functioning drivers were not around-but now i think there are a few options the new "amdgpu' pro beta or part of 16.60 for linux.
I have to wait though. I was trying to get the added driver support or card support drivers and my computer shut down in a reboot. stayed black, nothing happened and i smelled the acrid smoke
i had not touched the inside of the thing in 2months either. could be a AIO cooler pump failed and over heated , not sure though. have on the bench, no more Mint 18.1 for a bit.
but, thank you for replying
Again, i guess I wrote too much..sorry
john