Hi is there a way to get my R9 290X probably installed on my 10.12.5 Sierra.
I only have AMD HD 8xxx 4096 MB under "About my Mac"
Acceleration seems to be fine.
Download: IHex, IORegistry Explorer, and Kext Wizzard.
Open IORegistry Explorer and scroll down to the AMD4100kext and see which AMDcontroller kext is used. 9510, 8000, 7000 controller etc....
Once you know which controller kext it uses you can open it and edit the name.
1). Find the controllerkext in Systems/Library/Extensions and right click on it and choose "show package contents", next open the macOS folder and drag a copy of the controller to desktop. Make a copy and put in a folder in case of a mistake you can replace original.
2). Open iHex and drag desktop copy of controller to iHex then go to top menu bar under "Edit" scroll down to "Find" then scroll to the right in window that pops up and select "find".
3). On top of iHex window on the left side choose "text" and then type in the top find window HD 8xxx.
4). Now type in the replace window R9 290X, go to the right side of the iHex window and select "next" only hit it once and yellow highlighted script will apppear, then hit the " replace" tab only once. You should see a quick blur.
5). Save changes as you quit iHex and then drag the desktop edited copy of controller back to macOS folder of controller and follow the prompts "Authenticate and replace", if you don't get both of those hit cancel and drag it again.
6). Make sure to run Kext Wizzard before reboot. After reboot you should see R9 280X.