Quick update on this - just tried launching a few games and the distortion seen on the boot screen and windows login screen is repeated, covering most of the right half of the screen.  Monitor is effectively unusable at the moment.

Built on October 7, 2017. So they sold you an 8 month old monitor. Did they advertise it as NEW or refurbished?

"Amazon Marketplace is an e-commerce platform owned and operated by Amazon that enables third-party sellers to sell new or used products on a fixed-price online marketplace alongside Amazon's regular offerings."

* Run the stand alone BID (Built-in Diagnostics), page 40
* Take and post pictures of the colored full screens showing the issue
* If you do not see the issue on the stand alone BID colored screens, then the monitor itself is fine. The fault must be the computer, operating system, video card, video card driver, or cabling

Hi Chris, thanks so much for your reply and advice.

I have conducted some further tests.

I did not have an alternative PC to test the monitor with (my other computers are older and support DVI only) but realised we have a console with HDMI connection that would do the job, so I have tested the monitor with this and the problem persists. Again, oddly, the distortion is not present at all times - it is on the menu screen, but when I loaded up a game, it was not present (see screenshots in first link). With my PC, the distortion was present on boot screen, present on Windows login, not present on desktop (though other errors occurred when mousing to the edge of the screen), and was present on games.

I then conducted the BiD test again as advised which showed no obvious errors - pictures in second link, apologies for the angle of shot, my space is somewhat limited. I'm aware that the bad angle makes some of the colours appear off but can confirm that the colours were as expected and no screen errors were obvious.

So to summarise so far, the issue occurs on both PC (tested on 3x DP ports and 1x HDMI) and console (tested on HDMI), but the BiD shows no obvious errors. Unfortunately I do not have spare DP and HDMI cables to test for these, but the issue does occur on both types of connection.

As an aside, to correct my earlier statement, this monitor was actually purchased directly from Amazon, and was definitely sold as new. I have to amend back the third-party statement, with apologies for the mistake, which was a result of my misreading my invoice and confusing the seller with another part purchased at the same time.

Image when connected to console

BiD

Using the console and the GTX 1080 HDMI out port to the S2716DG HDMI in port =
* On the PC, G-SYNC should be turned OFF in the Nvidia Control Panel
* Open the S2716DG OSD (On Screen Display) Menu- Others
* Choose Factory Reset- Enable
* Go to Display
* Set Response Time to Normal
* The bottom should show =
Resolution: 2560x1440, 60Hz Normal Mode
* Then retest

Using the DP out on the GTX 1080 to DP in on the S2716DG =
* G-SYNC should be turned ON in the Nvidia Control Panel
* Open the S2716DG OSD (On Screen Display) Menu
* Go to Display
* Set Response Time to Normal
* The bottom should show =
G-SYNC, Resolution: 2560x1440, 144Hz G-SYNC Mode
* Then retest

If still not working, read this.

Thanks again Chris;

These are the settings I had been testing on; I have rechecked and the issue continues.

I think I will cut my losses and return the monitor to Amazon :)

Many thanks for your assistance!