If you put the used XFX GPU card in another computer and it has the same problem, It is a good indication that the GPU card may be bad.
Have you tried all the video outputs on the card to see if you get video on your monitor?
You must have at least a 450 watt PSU installed to run the GPU card. PSU REQUIREMENTS - RealHardTechX
Plus you need to uninstall completely all nVidia Graphics drivers from your computer which might cause some conflicts with the AMD Drivers. I would use DDU (Display Driver Uninstaller - Display Driver Uninstaller (DDU) V184.108.40.206 Released. - Wagnardsoft Forum ) in safe mode to remove all nVidia and AMD GPU drivers before installing AMD Drivers.
Follow this basic procedure to install AMD Drivers. If the AMD Driver set installs correctly than it is possible you have a hardware issue with the used XFX GPU Card.
install AMD driver:
1) Download the correct AMD Full Set of drivers from AMD Support. Make sure your Windows is fully updated via Windows Update. Windows Must be fully updated because the latest AMD Drivers requires all the latest "Optional" and "Recommended" updates to be installed.
2) Use Windows Uninstall to uninstall current AMD driver and software and disconnect the internet from your computer. Then use DDU (Display Driver Uninstaller) Display Driver Uninstaller (DDU) from Wagnardsoft Forum in Safe Mode. This will eliminate all traces of the AMD driver and software from your computer.
Delete C: \ AMD folder from the Root Directory. Reboot.
3) Go to Device Manager and click "Display Adapter" and make sure you are on the MS Basic Display Adapter. If not, uninstall the AMD driver using Properties.
4) Try reinstalling the AMD FULL SET OF DRIVERS that you have downloaded manually. Make sure you disable the Internet to prevent Windows from installing a newer version. So configure windows to prevent it from updating drivers via windows update. So it has been mentioned to disable any anti-virus programs before installing AMD Drivers.
5) If the new AMD drivers installs and works correctly, delete again the C: \ AMD folder from the root directory. To save space on the HDD.
6) Enable both the Internet and Anti-Virus program (if applicable).
7) Go back to Device Manager and check your GPU card driver is working and identified correctly.