Dell S2421HGF TN PANEL (6 BITS + FRC) – Dithering / Grainy Effect

[joaopikalisa]

Hello, guys. I recently purchased the Dell S2421HGF monitor, and I’ve noticed an issue with the image quality. The screen displays a sort of interference or static, creating a noticeable grainy effect. After conducting some tests, I found that the problem primarily occurs when the 144Hz refresh rate is enabled, which is one of the main features of this "gaming" monitor. The effect becomes more pronounced when I adjust the contrast to around 60% in the monitor's settings and display gray or black screens.

I’m fairly certain that the issue isn’t related to my machine, as I’ve tested four units of the same model, connecting them to different computers and laptops. The problem appeared on all of them, even when using a high-quality DisplayPort cable. The graininess is visible both on the Windows startup screen (including the default wallpaper) and while playing games.

I’ve tried several troubleshooting steps to address the issue, such as changing the power outlet, testing different HDMI and DisplayPort cables, and using alternative power cables for the monitor, but none of these attempts solved the problem. The grainy effect, or dithering, is always present, although its intensity varies depending on the color settings, refresh rate, and contrast adjustments in the monitor’s menu. I also installed the latest monitor driver from Dell’s website, but the issue persists.

It’s worth mentioning that I’ve tested four different units of the S2421HGF, which can be verified using the respective "Service Tags". I tested both the "Rev A00" and "Rev A02" versions, and the problem occurred with both. Based on this, I suspect that this might be a chronic issue with this model or possibly related to the type of panel it uses. It’s hard to believe that Dell, a renowned company in the monitor industry, would overlook such an obvious defect in their products.

My main question is whether this grainy effect (or dithering) can be resolved or if it’s an inherent characteristic of 6-bit + FRC panels. Additionally, I would like to know the correct technical term for this artifact or issue. Has anyone else experienced this problem with other Dell monitors? Out of the more than 10 monitors I’ve owned in my life, I’ve never encountered anything like this. When I tried uploading videos to show the problem, the compression process caused the effect to disappear in the recording. The only video I was able to share, which clearly demonstrates the issue, is on Instagram. In it, you can clearly see the grainy effect occurring on my screen without any intervention or alteration. (I can't post the video link).

I'm looking for help, or at least guidance, as I have a strong preference for monitors with TN panels. Although many prefer IPS or VA panels these days, TNs still meet my needs very well, especially when it comes to speed and response time. I'm currently using a Ryzen 7 5700X3D processor combined with a GTX 1660 Super graphics card * Win11 Pro 24h2 (is that the problem? An older GPU?). Although the overall performance is good, I have some doubts about the ideal type of monitor to get the most out of my setup. Can anyone help me with suggestions or shed more light on what might be affecting performance? Thanks in advance!

[kyube]

boop

Are you talking about a physical attribute of the coating, such as this


Or are you talking about this pixel inversion artifacts? They are sometimes very apparent on TN panels in particular
These 2 threads will help you take a look at what it exactly is:
viewtopic.php?f=19&t=3629&sid=a7ed73595 ... a227f67820
viewtopic.php?f=17&t=5346#p40978

IPS & VA LCD's have become very fast nowadays, there's no need to hesitate upgrading to good models just because they're not TN.