Hi,

I just purchased the S2721QS monitor from a Dell exclusive store in Greece (REV A01 - July 2020). 

I hooked it up using HDMI cable PROVIDED BY DELL with my laptop which has HDMI 2.0b and supports 5k@60hz output and I noticed that although 1920x1080@60Hz and 2560x1440@60Hz work fine, when I try to display 4K@60Hz the screen goes wild (although still recognizable) with very heavy horizontal flickering.

I believe that the HDMI cable provided by Dell is in fact HDMI v1.4 (Hotron 20276 E246588) and thus does not support 4k@60Hz. I cannot seem to find the spec sheet of that particular cable, but I did find a reference saying its 1.4.

Is there any chance I have damaged the monitor by forcing it to display 4k@60Hz with a bandwidth incompetent cable? I tried adjusting many settings via AMDs software and windows 10 settings before realizing that the cable must be at fault and it took a good ~30 minutes of intermittent flickering (I was going back to FHD changing some stuff, then back at 4k, etc.) - [Truth is I would have blamed the cable way earlier, but the fact that it worked on lower resolutions and the fact that it supported 4:2:0 subsampling (which HDMI v1.4 doesn't) confused me. Turns out AMDs drivers can make HDMI v.1.4 work with 4:2:0...]

I must say this has been a very disappointing experience for my first day of use. I honestly cannot understand how DELL decided it's appropriate to use a sub-optimal cable, without even warning the consumers that its not gonna work at the monitor's advertised resolution. Do bear in mind that the monitor does NOT support 24-30Hz, so an HDMI v.1.4 is completely incompetent of delivering 4K here.

I have not yet resolved the issue as I have no other HDMI 2.0 cables available right now, so I will update you tomorrow, but I am pretty sure that is the problem.

Regards,

Andreas

PS. While attempting to resolve the issue I installed the "DELL_S2721QS-MONITOR_A00-00_DRVR_KTRRG.exe" from the official Dell website. I, however, believe I messed up and actually downgraded my monitor (seeing as its A01). I suppose there's no way to revert that? I must wait patiently for the next file to be uploaded? Can anyone help me with that?