I had the same issue with the same Graphics card. After a few days of trial and error. Here's what worked for me.
Power off your laptop and keep it unplugged
Take out the battery
Hold the power button down for about 20 seconds
Plug back in the wall and/or put battery back in
Plug in the Hdmi to your laptop
Power on your computer
Your computer from this point may search and find the driver to run the Hdmi , mine did. Hope it works for you.