for the last year i have been unable to to use the HDMI port as my main screen port. It started with an update at the end on 2017 but was lucky enough to have an older install package on a harddrive, but i have since wiped that hd and forgot about not to update the software. and have lost all use of the HDMI port as a main screen
I have this or a very similar GPU, the Powercolor R9 380, which is really a repurposed R9 200. I am using Win 10 and the latest Adrenalin package fully recognizes the GPU. The HDMI works well, including the sound. Prior to using Win 10, I was using Win 8.1. I do seem to recall that Win 8.1 wanted a different driver, but now I am not so sure that the current Adrenalin would not have worked just fine.
Your post omits some important info needed to assist. What OS are you using? What version of driver are you currently using?
using win7 and Radeon Settings Version 2019.0910.1749.32088 , Driver Packaging Version 19.30.03.01-190910a-346974C-RadeonSoftwareAdrenalin2019
I am sure you are not looking forward to trouble shooting more than you already have, but .. Do you have another monitor to try? Even a TV that accepts HDMI input? The thing is to make sure that either nothing displays using the HDMI port, or that some devices do and others do not. Do you have another cable you can try?
Another thing, not very likely, but still possible. If there are more than two places to connect an HDMI cable, could it be you are on the wrong one?