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.
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?
Solved! Go to Solution.
I purchased the DeLock 84771 HDMI cable that supports 4K@60Hz.
The problem persists (even if i try to reduce the bandwidth required by using 4:2:0 subsampling with 8-bit color) as I cannot get rid of the horizontal flicker at 4K@60Hz. Additionally using high resolution video from my DSLR camera the flicker also seems to exist (although on a significantly less noticeable degree) at 1440p, so my initial blame on the HDMI cable provided by Dell was completely wrong.
I will be contacting Dell service on monday to return the monitor and get a full refund.
To what PC model is the S2721QS attached?
What GPU video card is in the PC?
What operating system is on the PC?
Driver KTRRG is only 349.95 KB. I doubt that it is "firmware update". When you ran it, did it provide the Windows operating system S2721QS INF, CAT, ICM files? When run, did you see any mention of "updating firmware" ?
The provided FVY5J HDMI to HDMI cable is 2.0 matching both of the HDMI 2.0 ports.