Well, the story ends here for the moment. I tried to swap the contents of the two monitors I had. This seemed successful but in the end, when I wanted to close the back, it didn't fit. The new motherboard is 10 mm shorter and 5 mm wider than the old motherboard. So the sub-D connector cannot reach the connector on the motherboard and I cannot use this monitor. Will try to get a beige 1084S-D2 monitor and try again.