Blur Busters Forums

Chief Blur Buster wrote:if GSYNC 120fps@120Hz looks worse than normal 120fps@120Hz

just tested it in cs:go. 120fps@120hz with or without g-sync looks 100% identical, no artifacts at all.

Well, thanks you all for answers. I think I can live with that without problem. <60fps is a shitty experience anyway

Aeon wrote:

Chief Blur Buster wrote:if GSYNC 120fps@120Hz looks worse than normal 120fps@120Hz

just tested it in cs:go. 120fps@120hz with or without g-sync looks 100% identical, no artifacts at all.

Well, thanks you all for answers. I think I can live with that without problem. <60fps is a shitty experience anyway

Ok, we ruled out a certain type of inversion defect, then!
If you see no inversion artifact difference between GSYNC and non-GSYNC at stable and high frame rates.

So, it appears that it is simply the varying of your refresh rate that's amplifying inversion artifacts.

This is a common problem on many VRR monitors, especially of the TN type.

That said, some TN panels do a much better job, so if you buy a different TN GSYNC monitor, you might (or might not) have far less inversion artifacts during variable situations.

If you want a monitor that doesn't have VRR-induced visibility of inversion artifacts, you may want to consider an IPS GSYNC monitor. There are pros/cons if you go this approach (Slower pixel response) but it's an option if you're heavily annoyed by inversion artifacts.

Can i ask why no one thinks this is FRC? I've have a 144hz G-Sync and have the same problem as this guy, when the framerate drops low enough you can see the dithering taking place, when you reach 50fps~ or whatever the FRC simply stops. I'm guessing because of the FPS doubling in G-Sync.

I'm thinking that maybe this is just due to the inefficient way they coded it in the G-Sync chip at the time.

@lexazootin,

I'm no expert on FRC, but I'd assume that it is a constant, passive process. The dithering may be more apparent with certain colors or color combinations (gradients, non-primaries, etc), but I'm not sure FRC would be so obviously affected by framerate or refresh rate.

Also, again, G-SYNC panels have quality standards, and 144Hz G-SYNC displays are almost always capable of a complete 30-144Hz range. The minimum refresh range (FPS doubling) usually only starts at 36Hz/FPS because it is the lowest direct divisible (without going below 30Hz) of 144Hz, so I don't think that is the cause either.

You're likely just seeing pixel inversion artifacts at lower refresh rates (where, as we've already stated, they would be exacerbated).

On some displays I've seen, FRC artifacts shows up as a random-noise dithering pattern on dark shades at lower refresh rates. And inversion aritifacts shows up as a regular pattern (e.g. fine checkerboard patterns, or horizontal/vertical lines). FRC is essentially temporal dithering, and that is more visible at lower refresh rates.

Usually, only one or the other is visible, but occasionally, on some displays, both can interact with each other to create an amplified artifact that's not visible with FRC only or inversion only. A superimposition of random noise (snow) and regular patterns. It doesn't always happen but it has happened before.

Inversion artifacts from imperfect inversion: If you see a checkerboard or regular pattern (horizontal lines or vertical lines), you are probably witnessing LCD inversion. These patterns may flicker erratically during udulations in refresh rate during VRR operation, especially at lower refresh rates.

FRC artifacts from FRC temporal dithering: The best FRC implementations use random-noise dithering (like DLP/plasma does) which has minimal interactions with inversion. If you see stationary-noise or random-noise (faint "analog TV snow" in dark greys at lower VRR refresh rates), you are probably witnessing FRC. FRC could also be ordered dithering patterns too, which would have more interaction problems with inversion artifacts. If they chose a very poor FRC pattern (e.g. ordered dither patterns), the two combined (FRC pattern + inversion pattern) can amplify the visibility of artifacts.

Ideally FRC and inversion logic should be completely invisible to human eye, but isn't always...

Just to add up some information to the topic.

I recently acquired an Alienware AW2518H 240hz and after some use I noticed that sometimes a very subtle checkered pattern appeared on screen during the game. I was already using the "Normal" response time mode since the Fast and Super Fast modes cause ghosting, so I was wondering what could this be. After playing Battlefield 1 today, which is a buggy mess and the framerate constantly drops to -60, I kept seeing this checkered pattern always when running through smoke or fog. If I stood still at some place, the pattern just went away. Since it was something caused by movement, I was suspecting it still had something to do with the response time, but after seeing the explanation on this topic and now knowing that is a well-known artifact caused by Gsync + pixel inversion, I think I'll have to deal with this from now on. But well, TN panels will suck one way or another.

The AW2518H is considered one of best gaming monitors ATM, but if this pixel inversion shows up so easily on low framerates with Gsync, I think it's not THAT good. Any slightest approach to the 60fps zone makes the checkered pattern easily visible, so if someone here is thinking about buying a 240hz monitor but is very afraid of pixel inversion, the AW2158H doesn't look like the better choice. Awesome monitor in any other aspect.

Thanks for your comments!

marcosrv wrote:but if this pixel inversion shows up so easily on low framerates with Gsync

Pixel inversion artifact. It's best to distinguish the two: pixel inversion versus pixel inversion artifacts.

Pixel inversion is in all LCD panels to prevent image retention issues -- Good pixel inversion is invisible (even at 30Hz and 60Hz too, all refresh rates). But when it becomes visible, it's an artifact of the pixel inversion behavior. It's electrically hard to 100% perfectly completely solve for many LCD panels.

marcosrv wrote:Any slightest approach to the 60fps zone makes the checkered pattern easily visible, so if someone here is thinking about buying a 240hz monitor but is very afraid of pixel inversion, the AW2158H doesn't look like the better choice. Awesome monitor in any other aspect.

Viewing distance is also a big variable too, and the framerate range of your game for your GPU horsepower too.
If your game varies a lot in framerate only above 80-100fps, it is less of an issue too. Varying framerates 80fps-240fps look much less problematic.