Hi Steven,

Please share the model number of the Dell XPS computer.

Have you tried another HDMI cable?
Does it show any message on the monitor such as 'Entering Power Save mode' prior to the display going out?
Does the display go out while in use or when idle?

Please also check for bent or broken pins in the HDMI cable connector.

Please try to perform factory reset on the monitor. Visit this link Factory reset settings and locate 'Other Settings'. Select 'Factory Reset' which resets all OSD settings to the factory default settings.

You can also try to update the video drivers by referring to this link: Video drivers
Enter the Service Tag (it is located at the top panel or at the back of the computer. It is 7 character code on a bar code label). >>Click Submit>> Select the operating system>> select 'Video' >> click the driver applicable for your computer.
Click on 'Download File'>> click "Download Now'>> Click 'Continue, Yes' on User Account control if prompted>>Click 'Continue' on the Application prompt>> Click 'OK' on Select the folder where you want to unzip the files to( Make a note of the folder location)>> Click 'Yes' on the next prompt for folder does not exist>> Click "OK' on All files were successfully unzipped. >> If the installation wizard does not appear, go to the folder location>> select the Setup file >> Right-click and select 'Run as Administrator">>Follow the installation wizard instructions. Reboot PC.

If this does not help, you can try to update the BIOS for the computer. Refer to this link: BIOS update . Enter the Service Tag>>Click Submit>> Select the operating system>> select 'BIOS' >> click the file 'Dell-BIOS'. Follow the aforementioned instructions for installing it. The computer will reboot after this update. Before flashing the BIOS please check the following:

* No external devices (except the keyboard, mouse and monitor) should be connected.
* All other programs should be closed and documents saved.
You can also refer to this link for User Guide

Hope this helps.
Do write back with the results.

Thanks and Regards,
Manpreet C