Try that HDMI port to a display over HDMI next as a test.
I have a MSI ATI HD 5450 Display Card.I'm Using a VGA monitor and when i try to connect another monitor trough HDMI port my screen starts to flicker and the device plugged/unplugged sound keeps playing but nothing appears on my second monitor.
(The control panel or the device manager does not recognize the second monitor)
I'm using a HDMI to VGA converter to connect my second monitor and both converter and the monitor works fine on other computers.
I'm using windows 10 pro with latest updates.

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