Flickering at 4k 3840 x 2160 60hz

[marskeiko123]

I am using a 2 way GTX 970 SLI setup and this monitor http://www.lg.com/hk_en/tvs/lg-42UB8200.

The problem that I am encountering is that in a game, the screen kept flickering/tearing when the resolution is set at 3840 x 2160 @ 60 Hz under PC using Nvidia control panel. If I change it to 4k x 2k 3840 x 2160 @ 30 Hz under Ultra HD,HD,SD, the games runs fine. FPS is at a stable 30fps.

I thought I needed to use HDMI 2,0 cable to enable 4k@60Hz however, even after getting a new cable today, the problem is still here. I am at complete lost on whether this is the TV's problem, or my graphic cards or the cable or the SLI bridge. Does anyone know a fix to this issue? Thank you.

Does it also have something to do with my TV only supports 4:2:0 chroma?

 

[marskeiko123]

I am still suffering from this problem, it will be much appreciated if someone can tell me how to solve it. I tried looking for posts regarding similar problem and I see one of the solution is to replace the SLI bridge. However, in the nvidia control panel, SLI is shown as enabled, so does that means the bridge is working correctly?

 

[Deyadissa]

I apologize for the really late response, but I feel I need to post this as I ran into the same problem with my setup and after hours of research and troubleshooting I've found out the problem. As you suspected, it is because your TV only supports 4:2:0 chroma; apparently the Nvidia drivers upscale a 4:2:0 signal into 4:2:2 natively on the computer which is pretty cool because you can't really tell a difference except for certain windows features don't render completely.

Anyways, you may have noticed some games work perfectly fine at 4k SLI, and other do not right? Well apparently, this issue only happens at 60hz, if the game runs at 59hz it will no longer flicker. So if you have a video game that only supports 60hz or doesn't give an option to change the refresh rate, you're out of luck; because even if you changed the resolution on the control panel... the video games STILL display at 60hz.

But here's the GOOD NEWS, I can fix this problem for you. What's the bad news? Well it is reported to NVIDIA but currently right now they do not have an ETA for a fix as of March. Another bad news is, once you fix this problem you'll not be able to use adaptive vsync anymore for the games that do not truly support 59hz. All other games that work fine now, adaptive vsync will work because it's running at 59hz already. Unfortunately, even though you are only losing less than a frame per second (because it is actually 59.996hz) it causes massive screen tears, you're forced to either use SMOOTH VSYNC or plain ole vsync, which unfortunately artificially reduces framerates. For example smooth vsync will drop your fps to 30fps, the second you go under 60fps and Vsync will drop you to 40fps; so you're going to have to sacrifice some video game settings to run 4k with SLI; it might be a better trade off to simply not use SLI for that video game. Note that some games truly support 4k at 60hz in SLI, but that is only because they don't run in full 4:4:4 chroma; these are usally MMO's or console games that want to push extra firepower.


Anyways, if you're interested in fixing this problem simply open up notepad on your computer and paste this in it

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\DirectDraw]
"ForceRefreshRate"=dword:0000003b

[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\DirectDraw]
"ForceRefreshRate"=dword:0000003b

Save it as a .reg file and double click to import it, reboot your computer and the games will now work in SLI.

 

[James25313]

I fix the screen issue if anybody wants to know here is how the fix it..

[video="https://www.youtube.com/watch?v=vHowP9gUsUE&feature=youtu.be&a="][/video]

I am using a 2 way GTX 970 SLI setup and this monitor http://www.lg.com/hk_en/tvs/lg-42UB8200.

The problem that I am encountering is that in a game, the screen kept flickering/tearing when the resolution is set at 3840 x 2160 @ 60 Hz under PC using Nvidia control panel. If I change it to 4k x 2k 3840 x 2160 @ 30 Hz under Ultra HD,HD,SD, the games runs fine. FPS is at a stable 30fps.

I thought I needed to use HDMI 2,0 cable to enable 4k@60Hz however, even after getting a new cable today, the problem is still here. I am at complete lost on whether this is the TV's problem, or my graphic cards or the cable or the SLI bridge. Does anyone know a fix to this issue? Thank you.

Does it also have something to do with my TV only supports 4:2:0 chroma?