Is it RTX 3080 limitation or Samsung Odyssey monitor issue. Hmm...

[Andrewtst]

Ok, today I play around again my monitors setting and I just notice one weird issue as I didn't connect 3 monitors previously when both my Odyssey is set as 240hz on monitor OSD.

 

I got 3 monitors.

• Samsung Odyssey Neo G8 (maximum 3840x2160 240hz)
• Samsung Odyssey Neo G9 (maximum 5120x1440 240hz)
• AOC 24G2SP (maximum 1920x1080 165hz).

Today I also notice toggle the Neo G8 VRR Control ON/OFF is actually kind of solved the Neo G8 scanlines issue! I know it sound weird same as using sRGB preset in SDR also solving the scanlines issue, but I do not prefer sRGB preset.

 

By toggle VRR Control ON/OFF, below is the result of scanlines issue in Neo G8.

• SDR - 95% solved, they are still little scanlines but not obvious unless you stick your face at monitor, previously is very obvious.
• HDR - 100% solved, cannot detect any scanlines issue.

I never had scanlines issue on Neo G9 after firmware update.

Since it is solved, I decide to use both my Neo G8 and Neo G9 in 240hz.

 

But then I found an issue, once I turn on both Neo G8 and Neo G9 to 240hz via monitor OSD, then my 3rd monitor 24G2SP always show disconnected and I cannot turn on at Windows 11 Display settings or choose all 3 monitors at Nvidia Control Panel. I can either turn on any 2 monitors out from 3 even I lower down all the refresh rate to 60hz. This is same case using DP or HDMI (no HDMI for Neo G9 as HDMI in Neo G9 only support 120hz). Reduce the refresh rate at Windows Display Settings or Nvidia Control Panel is not working as still cannot choose more than 2 monitors but change one of the Odyssey monitors to 120hz via monitor OSD solved this issue.

 

So, I decide to reduce my Neo G9 to 120hz at monitor OSD instead of 240hz but not on Neo G8 as

• Neo G9 accepted custom refresh rate of 165hz.
• Neo G8 only accepted custom refresh rate of 136hz.

After playing around. I can only set as below as max.

• Samsung Odyssey Neo G8 (max at 10-bit 3840x2160 240hz)

• Samsung Odyssey Neo G9 (max at 10-bit 5120x1440 with custom refresh rate of 165hz)

• AOC 24G2SP (max at 8-bit 1920x1080 165hz).

 

Beside above issue, they are one more issue I notice it long ago.

• Same DP 1.4 cable but only work at Neo G8 240hz and not Neo G9 240hz as it keeps badly flickering.
• Another DP 1.4 cable work at both Neo G8 240hz and Neo G9 240hz without single flickering and perfectly fine.

 

I wonder is this limitation of RTX 3080 or Samsung Odyssey monitor issue.

This two Samsung Odyssey monitor had many funny patterns. Hmmm... 

 

[Fred Castellum]

I'm 90% sure your running into a 3080 limitation. You might have to lower the bitrate on your monitors, refresh rate or resolution. I've seen similar compatibility issues with multiple high res, high refresh rate monitors. 

[Agall]

42 minutes ago, Andrewtst said:

Ok, today I play around again my monitors setting and I just notice one weird issue as I didn't connect 3 monitors previously when both my Odyssey is set as 240hz on monitor OSD.

 

I got 3 monitors.

• Samsung Odyssey Neo G8 (maximum 3840x2160 240hz)
• Samsung Odyssey Neo G9 (maximum 5120x1440 240hz)
• AOC 24G2SP (maximum 1920x1080 165hz).

Today I also notice Neo G8 didn't turn on VRR but my Neo G9 is on, so I decide turn the VRR ON and viola! doing this actually kind of solved the Neo G8 scanlines issue! I know it sound weird same as using sRGB preset in SDR also solving the scanlines issue, but I do not prefer sRGB preset.

 

By turn VRR ON, before is the result of scanlines issue in Neo G8.

• SDR - 95% solved, they are still little scanlines but not obvious unless you stick your face at monitor, previously is very obvious.
• HDR - 100% solved, cannot detect any scanlines issue.

I never had scanlines issue on Neo G9 after firmware update.

Since it is solved, I decide to use both my Neo G8 and Neo G9 in 240hz.

 

But then I found an issue, once I turn on both Neo G8 and Neo G9 to 240hz via monitor OSD, then my 3rd monitor 24G2SP always show disconnected and I cannot turn on at Windows 11 Display settings or choose all 3 monitors at Nvidia Control Panel. I can either turn on any 2 monitors out from 3 even I lower down all the refresh rate to 60hz. This is same case using DP or HDMI (no HDMI for Neo G9 as HDMI in Neo G9 only support 120hz). Reduce the refresh rate at Windows Display Settings or Nvidia Control Panel is not working as still cannot choose more than 2 monitors but change one of the Odyssey monitors to 120hz via monitor OSD solved this issue.

 

So, I decide to reduce my Neo G9 to 120hz at monitor OSD instead of 240hz but not on Neo G8 as

• Neo G9 accepted custom refresh rate of 165hz.
• Neo G8 only accepted custom refresh rate of 136hz.

After playing around. I can only set as below as max.

• Samsung Odyssey Neo G8 (max at 10-bit 3840x2160 240hz)

• Samsung Odyssey Neo G9 (maxi at 10-bit 5120x1440 with custom refresh rate of 165hz)

• AOC 24G2SP (max at 8-bit 1920x1080 165hz).

 

Beside above issue, they are one more issue I notice it long ago.

• Same DP 1.4 cable but only work at Neo G8 240hz and not Neo G9 240hz as it keeps badly flickering.
• Another DP 1.4 cable work at both Neo G8 240hz and Neo G9 240hz without single flickering and perfectly fine.

 

I wonder is this limitation of RTX 3080 or Samsung Odyssey monitor issue.

This two Samsung Odyssey monitor had many funny patterns. Hmmm... 

 

I have a Neo G8 so I can at least discuss that.

 

I stuck with DP on mine after starting with HDMI, noticeable input latency. You're using DSC to reach 240Hz though I haven't ever run into an issue with it on DP.

 

If you're forcing Nvidia color settings and 10bit/HDR on the Neo G8, that might be part of the problem, otherwise VRR+240Hz with DP1.4 DSC shouldn't have issues.

 

You're operating on the extreme trying to drive 4K@240Hz, 5120x1440@240Hz, and 1080p@165Hz all at the same time, so I wouldn't be surprised if that's just exceeding a bandwidth limitation on display out for any card.

[Fred Castellum]

11 minutes ago, Agall said:

You're operating on the extreme trying to drive 4K@240Hz, 5120x1440@240Hz, and 1080p@165Hz all at the same time, so I wouldn't be surprised if that's just exceeding a bandwidth limitation on display out for any card.

Yeah that's a ton of pixels to drive at once, if you have a iqpu you could split usage on that if said monitor isn't gaming required. Would definitely help with bandwidth. 

[Andrewtst]

27 minutes ago, Fred Castellum said:

You might have to lower the bitrate on your monitors

Thanks for the information. I will try out.

11 minutes ago, Agall said:

HDMI, noticeable input latency

Not only that issue, I also notice G-sync is not working when using HDMI in 240hz, I also switch back all to DP now.

12 minutes ago, Agall said:

exceeding a bandwidth limitation

Thanks for the information, it seems bandwidth limitation of 3080 then.

[Fred Castellum]

1 minute ago, Andrewtst said:

Thanks for the information. I will try out.

Not only that issue, I also notice G-sync is not working when using HDMI in 240hz, I also switch back all to DP now.

Thanks for the information, it seems bandwidth limitation of 3080 then.

It's unfortunate, but I ran into similar problems a while back when I tried hooking up a 3rd monitor myself. I run a 4k, and a 1440p ultrawide. Tried to throw another higher res ultrawide into the mix and the 4080 I'm using just had problems in general. Refresh rate and picture quality all play into bandwidth. 

40 series cards seem to handle a bit more than 30 series, but both gen of cards have limitations with running multiple increasingly larger monitor resolutions at once. 

[Agall]

12 minutes ago, Andrewtst said:

Thanks for the information. I will try out.

Not only that issue, I also notice G-sync is not working when using HDMI in 240hz, I also switch back all to DP now.

Thanks for the information, it seems bandwidth limitation of 3080 then.

Unsure of how accurate this is to a GPU's actual display output bus, but if you calculate the total pixels/second of those displays at their given refresh rate, it comes out to 4.10 Gpixel²/sec and techpower lists the spec at 

Theoretical Performance

Pixel Rate

164.2 GPixel/s

[Andrewtst]

1 minute ago, Fred Castellum said:

It's unfortunate, but I ran into similar problems a while back when I tried hooking up a 3rd monitor myself. I run a 4k, and a 1440p ultrawide. Tried to throw another higher res ultrawide into the mix and the 4080 I'm using just had problems in general. Refresh rate and picture quality all play into bandwidth. 

40 series cards seem to handle a bit more than 30 series, but both gen of cards have limitations with running multiple increasingly larger monitor resolutions at once. 

Thanks for this value input, I will take noted on that, lucky I didn't purchase another higher resolution for my 3rd monitor.

[AI_Must_Di3]

IMO, you are bumping up against the max ability for the 3080, but really any gpu for the most part, at 7680 x 4320, BUT now you have to factor in the displayport specs cause you arent getting over 120hz with ANY hdmi options, not yet anyway. So far DP does 4k at 240hz, 8k at 85hz. Now, they do have this listed that may help you:

 

"When using only two lanes on the USB-C connector via DP Alt Mode to allow for simultaneous SuperSpeed USB data and video, DP 2.0 can enable such configurations as:Three 4K (3840×2160) displays @144Hz and 30 bpp 4:4:4 HDR (with DSC)
Two 4Kx4K (4096×4096) displays (for AR/VR headsets) @120Hz and 30 bpp 4:4:4 HDR (with DSC)
Three QHD (2560×1440) @120Hz and 24 bpp 4:4:4 (no compression)
One 8K (7680×4320) display @30Hz and 30 bpp 4:4:4 HDR (no compression)"

 

Thats from their official faq: https://www.displayport.org/faq/#tab-displayport-2-1-standard 

 

Of course any graphics card you buy is going to have that 7680 x 4320 display wall, and its been that way for awhile.

[Agall]

1 minute ago, AI_Must_Di3 said:

IMO, you are bumping up against the max ability for the 3080, but really any gpu for the most part, at 7680 x 4320, BUT now you have to factor in the displayport specs cause you arent getting over 120hz with ANY hdmi options, not yet anyway. So far DP does 4k at 240hz, 8k at 85hz. Now, they do have this listed that may help you:

 

"When using only two lanes on the USB-C connector via DP Alt Mode to allow for simultaneous SuperSpeed USB data and video, DP 2.0 can enable such configurations as:Three 4K (3840×2160) displays @144Hz and 30 bpp 4:4:4 HDR (with DSC)
Two 4Kx4K (4096×4096) displays (for AR/VR headsets) @120Hz and 30 bpp 4:4:4 HDR (with DSC)
Three QHD (2560×1440) @120Hz and 24 bpp 4:4:4 (no compression)
One 8K (7680×4320) display @30Hz and 30 bpp 4:4:4 HDR (no compression)"

 

Thats from their official faq: https://www.displayport.org/faq/#tab-displayport-2-1-standard 

 

Of course any graphics card you buy is going to have that 7680 x 4320 display wall, and its been that way for awhile.

Also running two displays via DP 1.4 DSC may be a problem.

[Andrewtst]

8 hours ago, AI_Must_Di3 said:

arent getting over 120hz with ANY hdmi options,

I not sure on this, Neo G8 do can set up to 4K 12-bit @ 240hz using HDMI 2.1 cable. The Neo G9 wise only 12-bit @ 120hz.

 

Using HDMI 2.1 at Neo G8 and DP 1.4 at Neo G9 also same cannot add 3rd monitor if both also set 240hz even on 10-bit.

8 hours ago, AI_Must_Di3 said:

DP 2.0

Too bad my both monitor is only DP 1.4, also 3080 is not support DP 2.1 as well.

[Andrewtst]

8 minutes ago, Agall said:

Also running two displays via DP 1.4 DSC may be a problem.

2 display using DP 1.4 DSC so far ok, no issue.

[Agall]

14 minutes ago, Andrewtst said:

I not sure on this, Neo G8 do can set up to 4K 12-bit @ 240hz using HDMI 2.1 cable. The Neo G9 wise only 12-bit @ 120hz.
for DP, only 10-bit.

Too bad my both monitor is only DP 1.4, also 3080 is not support DP 2.1 as well.

Keep in mind that the Neo G8 only supports DP 1.4 and HDMI 2.1, so higher DP2.x version aren't supported on that display even if the GPU supports it.

[Andrewtst]

9 minutes ago, Agall said:

Keep in mind that the Neo G8 only supports DP 1.4 and HDMI 2.1, so higher DP2.x version aren't supported on that display even if the GPU supports it.

Ya, I know. That why I said both monitor only DP 1.4, and so far I think only AMD 7900 XTX support DP 2.x

[Andrewtst]

16 hours ago, Fred Castellum said:

You might have to lower the bitrate on your monitors

Just try, lower down the bitrate did not help.

 

I even reduce both Odyssey to the lowest of YCbCr 4:2:2 and 8 bcp also cannot, as long both monitor set as 240hz, then the 3rd monitor will be disconnected and can choose 2 out of 3 monitors only at Nvidia Control Panel.

[Fred Castellum]

7 hours ago, Andrewtst said:

Just try, lower down the bitrate did not help.

 

I even reduce both Odyssey to the lowest of YCbCr 4:2:2 and 8 bcp also cannot, as long both monitor set as 240hz, then the 3rd monitor will be disconnected and can choose 2 out of 3 monitors only at Nvidia Control Panel.

Yeah refresh rate is too high. I gave up running 3, returned the third one. Not much you can do about the limitation unless you lower settings or get other hardware to supplement it. 
 

 

[Andrewtst]

8 hours ago, Fred Castellum said:

Yeah refresh rate is too high. I gave up running 3, returned the third one. Not much you can do about the limitation unless you lower settings or get other hardware to supplement it. 
 

 

I decide lower down one of the Odyssey to120hz and keeping the 3 monitors.

[Fred Castellum]

19 minutes ago, Andrewtst said:

I decide lower down one of the Odyssey to120hz and keeping the 3 monitors.

Gotta do what you gotta do. At least it works now?

[Andrewtst]

5 hours ago, Fred Castellum said:

Gotta do what you gotta do. At least it works now?

It works but cannot set both Odyssey at 240hz.

 

Final setting now, I reduce Neo G9 to 144hz as the custom resolution 165hz make my PC unable to wake up after monitor goes to sleep mode.

• Samsung Odyssey Neo G8 (10-bit 3840x2160 240hz)

• Samsung Odyssey Neo G9 (10-bit 5120x1440 144hz)

• AOC 24G2SP (max at 8-bit 1920x1080 165hz).

[Fred Castellum]

6 hours ago, Andrewtst said:

It works but cannot set both Odyssey at 240hz.

 

Final setting now, I reduce Neo G9 to 144hz as the custom resolution 165hz make my PC unable to wake up after monitor goes to sleep mode.

• Samsung Odyssey Neo G8 (10-bit 3840x2160 240hz)

• Samsung Odyssey Neo G9 (10-bit 5120x1440 144hz)

• AOC 24G2SP (max at 8-bit 1920x1080 165hz).

Glad you got the settings they will work together with ironed out. You should take a picture of the setup in all it's glory to show off to us lol.

[Andrewtst]

13 hours ago, Fred Castellum said:

Glad you got the settings they will work together with ironed out. You should take a picture of the setup in all it's glory to show off to us lol.

Just a simple setup.

 

 

[Fred Castellum]

1 hour ago, Andrewtst said:

Just a simple setup.

Man that's a sick setup

[Andrewtst]

Not sure how the Nvidia / Windows calculate and set.

 

By using HDMI 2.1

• I can set my Odyssey Neo G8 @ 12-bit 240hz, Odyssey Neo G9 @ 12-bit 120hz and 24G2SP @ 8-bit 165hz and all 3 monitors is connected. 
• (82.27 + 34.26 + 9.55 = 126.08 Gbit/s) and bandwidth requirement here is much higher.

 

• But only 2 monitors are connected even I lower down both Odyssey monitors to 8-bit @ 240hz.
• (54.84 + 48.49 + 9.55 = 112.88 Gbit/s) which showing less bandwidth requirements as above.

 

[Glenwing]

4 minutes ago, Andrewtst said:

Not sure how the Nvidia / Windows calculate and set.

 

By using HDMI 2.1

• I can set my Odyssey Neo G8 @ 12-bit 240hz, Odyssey Neo G9 @ 12-bit 120hz and 24G2SP @ 8-bit 165hz and all 3 monitors is connected. 
• (82.27 + 34.26 + 9.55 = 126.08 Gbit/s) and bandwidth requirement here is much higher.

 

• But only 2 monitors are connected s even I lower down both Odyssey monitors to 8-bit @ 240hz.
• (54.84 + 48.49 + 9.55 = 112.88 Gbit/s) which showing less bandwidth requirements as above.

If it's a limitation internal to the GPU then most likely there is some pixel rate limit, not a flat bit rate limit.

[Andrewtst]

6 hours ago, Glenwing said:

If it's a limitation internal to the GPU then most likely there is some pixel rate limit, not a flat bit rate limit.

Oh! I never know or thought about that, thanks for this information.

I think GPU need to increase it limitation to allow at least 3 units of 4K monitors set as 10-bit 240hz.

 

By the way, I already set back both monitor to 10-bit as I notice 12-bit seems a bit slow respond and also the color seems a bit flat and no pop especially like reduce nits in bright object at HDR content. So I think the best still 10-bit for the moment.