New HP Z24n G2 monitor shows 7mm borders left and right

[wilfredb]

Hello, I just bought a new 24" HP 24N G2 monitor. I am pretty satisfied with it, next to (and compared to) my old HP ZR24w , which is now functioning as second monitor. The 24N is connected to my PC using the HDMI connection from a Geforce GT 710.

I now notice that I have wide margins on the screen, both left and right, showing as extra black borders. The distance between the outer monitor edge and beginning of the pixels is 7 mm. I would expect that distance to be about 2 mm: the width of the besel. So the screen pixels are not starting right from the edge. 

I looked at the monitor menu to see if I could make the shown screen 'wider', so to fill the screen up to the edges, but the option 'Image scaling' (which I expect is the one I would need) is grayed-out, not available.

I made a photo of the edge, in the lower-left corner, while using the Nvidia control panel option to change screen size:

Border lower left

That Nvidia tool does also not solve the problem, I can only make the screen more narrow, not provide more 'width'.

I had to do a factory reset of the monitor, because when I woke my PC from sleep this morning, the monitor was flashing full-screen colors; blue red green white. I was startled but after some searching I found (see https site:  support.hp.com/ca-en/document/c00791958) that this was a kind of pre-shipping setting which has to be removed using the factory reset. So I did. I am not sure anymore if the extra border also appeared already before this factory reset.

Is this supposed to look like this?  I hope not, since one of reasons I preferred this monitor was the 'narrow bezel'.

How can I use the full width of the monitor?