Dell Inspiron 15-3521 HDMI port not working after windows downgrade

I have a new Dell Inspiron 15-3521 laptop that came with windows 8 installed. We removed 8 and installed a fresh copy of windows 7 professional. We pulled all of the application, driver, and bios files off of the dell website and installed in the order suggested. Everything is working great other than when we plug the hdmi port into a projector or other monitor it does not recognize it in any way.

Any idea what driver we are missing or why this isn't working? We've tried adjusting resolution and detecting the 2nd monitor every way we can.

Thanks.