S2721HN, HDMI only partitally functions using HDMI

@fmbarch  Is your XPS PC a laptop rather than an XPS desktop? If so, then if the laptop’s display is also active, what you’re describing is the completely normal functionality of a multi-display setup in Extend mode. The background image is replicated across all displays (unless you enable per-display backgrounds), the taskbar along the bottom is also displayed on all displays and its content can either be replicated or configured to show only applications actually running on that specific display, desktop icons by default are only on the display designated as primary (which you can choose in Windows Display Settings), and applications can be dragged onto whichever display you want to see then on. Essentially you’ve just expanded your total workspace, but you have to decide where you want to put your applications.

If you wanted to mirror the built-in display to the external display, or use ONLY the external display when it’s connected, then you can choose those modes of operations as well if you’d like. Again, go to Windows Display Settings for this. That will also allow you to specify the relative position of each display so that you can drag application windows across the correct edge of the displays to move them over to the other display if you stick with Extend mode. So for example if your laptop display is physically to the left of your external display, Windows needs to know that. Same if it’s on the right. Otherwise moving windows or even the cursor between your displays will be a bit unnatural.

Thanks for the response but my Dell XPS PC is a desktop and I only had one monitor connected at a time and what I described is what I got. How do I fix this

@fmbarch It sure sounds like Windows at least THINKS there's some other display attached.  Does Windows Display Settings indicate that it believes two displays are connected?  What was your previous setup that worked as expected?  Does that setup still work as expected, assuming it's still available to test?  In fact if you can connect both displays at the same time, I'm curious what would happen if you did that and then designated your new HDMI display as primary.  But this definitely isn't going to be a compatibility issue.  Your new display is only 1080p, and that resolution has been supported for literally decades, and HDMI has supported it since HDMI was introduced.  And even if it were a compatibility issue, you'd see issues such as no video or an unstable video signal.  An HDMI issue wouldn't be able to cause an issue such a desktop icons not appearing even though it presents other content properly.

That’s odd that windows would think there is more than one monitor connected. The set up since I got the desktop has been only one monitor only connected by a VGA cable and it has worked fine.  There has never been more than one monitor hooked up. The Windows Display screen only shows one monitor when I had only the new monitor set up and only one when I have the old one. With the old one I used both the VGA and then the HDMI setup and each time it only snows one monitor.  If I hooked them both up at once how would I designate one as primary? If I did that and lost the Windows Display page I would be in a bad situation if the new monitor did not show open programs.  Has this ever happened before?

@fmbarch  When you have multiple displays, a diagram of a multi-display layout appears at the top of Windows Display Settings so you can drag the displays in the diagram around to match their physical positioning, and when you select a display, you’ll have a checkbox that says “Make this my primary display”. You can’t “lose” one because if the primary display goes offline, then Windows automatically uses one of the remaining displays as primary. This isn’t a hazard because it happens all the time in laptop scenarios where users might want to use an external display as primary while connected to one, but of course they might take their laptop away from their desks. They don’t have to do any special preparation for that.

But if Windows isn’t indicating that multiple displays are connected, and yet still isn’t showing your desktop icons, AND connecting the original display still causes everything to work as expected, that’s a new one for me. If you don’t want to try the multi-display solution I just proposed above, then I guess you could try fully uninstalling and reinstalling your GPU drivers. But I would try the multi-display option first, in fact if you have the desk space, you might want to simply use multiple displays permanently. It’s one of those things where once you’ve experienced it, it’s practically impossible to go back.

Thanks,  I'll try the double monitor hookup in a day or two.

I need more time to set up the dual monitor.  Been tied up with the holiday celebrations.