Samsung 24" FHD Monitor with Bezel-LESS Design - LS24R350FHNXZA
I can only vouch for the quality or lack of for the tested monitors in
my Best Reviewed Flicker Free Buying Guides, or check the review sites
linked to here.
When I try that PWM test page, I get a "sync failure" error at the bottom, which is telling me to move all my apps to my primary monitor.
Set the 25er to the primary monitor. Desktop Right Click>Displays>Scroll down and click the Make This My Main Display Box.
Now my HP 25er is starting to fail. Losing focus? I don't know how to term it except that I can see very faintly horizontal lines. The backlight has only about 13,000 hours.
I tried changing the cable, and it looks the same in the BIOS as in the OS. Just has a subtle grainy look about it now.
Call or email HP and see if they will exchange it or take it for repair.