Questions regarding « brightness flickering » under VRR

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  • #69158
    ppn7

      Hi,

      First of all, I would like to thank you for your website and this forum which is full of useful informations !

      Then I would like to talk about Freesync/Gsync flickering in general. Particularly the one which is called « brightness flickering »
      I found that it is due to variation in refresh rate. And the brightness is not the same at low or high refresh rate. So when I use Gsync/Freesync, if LFC kick in it will jump just for example from 50Hz to 100Hz. Sometimes even if it’s in the range, it will jump to the maximum refresh rate as if Gsync/Freesync was disabled for a second.

      I wonder if this brightness variation is valid for all type of monitor ? Does Gsync module manages this issue ? I thought it was only for VA panel but mine is an IPS one.

      I thought I could just play without Vsync but finally I can see tearing and Vsync ON without stable frametime is juddering.

      So I hope I can find a 1080p/144Hz/IPS without this issue. And I know people won’t necessarily be sensitive to this flickering like I’m not sensitive to interlaced patterns.

      Thanks !

      #69161
      PCM2

        Glad you’re finding it helpful!

        The issue with what could broadly be called ‘VRR flickering’ can manifest in various ways. It can be caused by a panel’s sensitivity to the voltage fluctuations that occur when the refresh rate changes, particularly large changes that would occur for example when the LFC boundary is crossed. VA models are usually particularly prone to this. Occasionally IPS models will have this issue, but it’s not widespread there. G-SYNC modules offer more careful voltage regulation and tighter tuning and will generally eliminate this form of VRR flickering with any panel type. It can also be caused, to a more minor degree in most cases, by slight shifts in gamma as refresh rate changes in a VRR environment. These shifts usually occur for darker to medium-dark shades when significant fluctuations occur and can even be observed on OLED models – for example, this occurs on the Dell Alienware AW3423DW even though it has a G-SYNC module. Most IPS models are free from this sort of VRR flickering as well.

        There are a few exceptions and it seems you own one such model. I used to have various issues with ‘G-SYNC Compatible’ on my old GTX 10 series GPU as well, which instantly vanished when upgrading to an RTX 30 series GPU. So this can have an impact in some cases. What are the monitors you’re having issues with and what GPU are you using? Do you see it when running this flickering test, specifically, which shows various grey levels whilst frame rate (and hence refresh rate under VRR) fluctuates significantly? The AOC 24G2(U), for example, sometimes seems to exhibit flickering under VRR, although it seems to vary between units. From the feedback I’ve received on this one it might be something of a combination of both flickering types there. The newer 24G2SP(U) I tested did not exhibit this and I haven’t seen any specific reports that it is affected in this way. It’s something I’ve specifically tested for a while now and will comment on (if it’s there) – and having reviewed a broad range of IPS models I can confidently say that it’s rarely an issue.

        #69166
        ppn7

          Thank you for the detailed response.

          Actually i have the 24G2U v1. I tried the VRR test you provided to me. And I can definitely see the flickerings. I use it with a RTX 3060Ti. In fact i can also see interlace patterns at 60Hz, very less noticeable at >60hz but it doesn’t bother.
          I tried the pendulum demo by Nvidia, in the 60-140Hz range, it works well without flickering but as soon as i approach the 48Hz limit, it will spike and flicker.
          But in-game i don’t know even the frametime stable it will flicker.

          But if i understand, there are monitors that will not flicker even if i get into the LFC ? Like the 24G2SP(U) sample you had tested ? I mean this one had no flickering issue in the VRR test, right ?

          I tried a tip provided somewhere in reddit or else where i don’t remember, which is to change CRU range, from 48-144Hz to 72-144Hz for example and capslock to 60fps to stay always into LFC mode, but it doesn’t work properly, it will jump to 144Hz and flicker but less visible since from 120Hz and 144hz brightness will be almost the same.

          Let me show you some example it you allow me here :
          Gsync range 48-144Hz
          Gsync range 72-144Hz
          Pendulum Demo – LFC 60 FPS NVCP cap – No flickering
          TW3 – LFC 60 FPS NVCP cap – Flickering

          Too bad for me that when i bought this monitor 2 years ago, i didn’t have a freesync or gsync compatible GPU to test it. Next time i will for sure check this day one !

          #69168
          PCM2

            Yeah, it’s definitely that jump from ~60Hz to ~120Hz when LFC kicks in that does it. Or with additional fluctuations that are large enough to set it off (the VRR flickering test will specifically cause a few of these wild fluctuations). Indeed that shouldn’t happen and with most models it won’t happen – as we describe in reviews, the normal behaviour there is to have subtle momentary stuttering at the boundary but there shouldn’t be flickering.

            #69173
            ppn7

              Thank you, i will give a try to RMA. I don’t know if i will be refund but i hope, then i will try to buy something else, maybe the 24G2SPU or BenQ EX2510(S)/Acer equivalent.

              But i saw that you warned about red issue with the S version of the EX 2510

              #69189
              ppn7

                Hi.

                My RMA is activated. AOC is going to send me a new unit and they will pick up the old.
                Really surprised by their reactivity.
                I’ll keep you informed and let you know which version I’ll get. And of course if the issue is solved or not.

                Thanks.

                #69206
                ppn7

                  Hi.

                  Just a quick resume. I did my RMA so I quickly receive my new unit. And I’m really satisfied that I don’t see any flickering at all. So the first one was defective for sure.

                  Really surprise by AOC warranty.

                  It’s a V1 same panel but with a new FW (firmware ?)

                  Old one

                  New one

                  #69208
                  PCM2

                    That’s great to see! Really glad you’re happy with your new 24G2U and it doesn’t have the VRR flickering issue. And also that AOC facilitated the swap under warranty so smoothly for you without giving you the (in some ways inferior) BOE panel they briefly used. 😀

                    #69660
                    skuko

                      The issue with what could broadly be called ‘VRR flickering’ can manifest in various ways. It can be caused by a panel’s sensitivity to the voltage fluctuations that occur when the refresh rate changes, particularly large changes that would occur for example when the LFC boundary is crossed. VA models are usually particularly prone to this. Occasionally IPS models will have this issue, but it’s not widespread there. G-SYNC modules offer more careful voltage regulation and tighter tuning and will generally eliminate this form of VRR flickering with any panel type. It can also be caused, to a more minor degree in most cases, by slight shifts in gamma as refresh rate changes in a VRR environment. These shifts usually occur for darker to medium-dark shades when significant fluctuations occur and can even be observed on OLED models – for example, this occurs on the Dell Alienware AW3423DW even though it has a G-SYNC module. Most IPS models are free from this sort of VRR flickering as well.

                      Hey PCM2, long time no read.

                      I just got my 3423DW and i do experience this:

                      https://www.youtube.com/watch?v=84XVamTu_po

                      (not my video, but the issue is the exact same)

                      the title is Lost Ark, you can replicate this by just pressing escape to get the menu on screen. it darkens the rest of the image, which i assume causes this flicker.

                      the FPS on my end is 172 (capped via RTSS). it is eliminated by turning gsync off.

                      my question would be – is this the VRR flicker you mention and secondly, if it’s eliminated by turning off g-sync, is this a sign of a faulty module and should it in your opinion be grounds for a replacement?

                      #69662
                      PCM2

                        Hi skuko and welcome back,

                        This is the sort of VRR flickering behaviour covered in this thread and also the AW3423DW review (written and video). It’s a typical characteristic for OLED due to the extreme contrast and not related to a G-SYNC module fault. Something you might think could be corrected by a G-SYNC module with appropriate gamma correction, sadly not in this case. Game menus are a typical time when this will happen and be obvious due to large areas of static content, medium-dark to dark shades being present and the fact the refresh rate is usually fluctuating rapidly (even if just cycling quickly between a few different values).

                        #70375
                        PCM2

                          A Twitter follower has noted that the AW3423DWF suffers more noticeable VRR flickering than the AW3423DW. I’ve seen similar reports on Reddit from those with experience of both models. Coming back to what I said in my initial post on this thread about G-SYNC modules allowing more careful voltage regulation, I suspect the ‘DWF’ has issues in that regard which are eliminated by the module of the DW. It’s a shame they didn’t include more careful gamma compensation to eliminate all forms of VRR flickering on the ‘DW’. It’ll be interesting to see if the other non-G-SYNC QD-OLEDs clearly suffer in a similar way. Early reports suggest the Samsung Odyssey OLED G8 suffers from obvious VRR flickering, too.

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