Do the displays have a DP 1.2 mode switch? That can do 4K60 10bpc without DSC.

DP 1.3 has the bandwidth of DP 1.4 but without DSC. Does it have a DP 1.3 mode?

The Nvidia limitation with DSC is described in
https://nvidia.custhelp.com/app/answers/detail/a_id/5338/~/using-high-resolution%2Frefresh-rate-displays-with-vesa-display-stream

It seems to indicate that you might get around that by using a lower bandwidth display mode. Try selecting 4K60 for each display. If that works, then maybe you can try higher resolutions. 4K95 is the max CVT-RB timing for 10bpc. 4K118 is the max CVT-RB timing for 8bpc.

Display Stream Compression capability is described in the DCPD info of DisplayPort. You would need a DPCD emulator to override that. Or a driver patch.

I suppose a DisplayPort MST hub would just pass through DSC even if the hub doesn’t support DSC itself?

A DisplayPort to HDMI 2.0 adapter will negate DSC. HDMI 2.0 can do 4K60 8bpc.

Hello, the monitor doesn’t have a “turn off DSC” option or a DP mode switch.

DP to HDMI 2.0 is not an option for me I’m affraid. I can’t run 144Hz monitors with 60Hz, they cost 1000 EUR each. I could live with 95Hz.

The problem is that DSC is on from the start, so no matter what I try in terms of lower refresh rates; they won’t turn on (of more than 2 are connected at the same time). Even If I set it before (when only 2 are connected) and then use 3 again.

I tried using the Custom Resolution Utility and deselected all display stream compression checkboxes in the data blocks of HDMI and DP. No luck, I guess because the GPU queries the monitors prior to the OS and is then locked in… 

If only MSI would provide users with a firmware allowing them to turn of DSC (like they did with so many other models, this one is also still a current model).

Then I could connect two monitors with DSC disabled (1 via HDMI 2.1, I guess I could even run 144Hz 10bit there), and one with DP at I guess 95Hz max. The third one would work with DSC and then all 4 heads of the 4090 would be used.

Or alternatively I could run all 3 monitors without DSC at the same refresh rate.

But there is no firmware update for my monitors 🙁

suppose a DisplayPort MST hub would just pass through DSC even if the hub doesn’t support DSC itself?

I wouldn’t know, that’s why I asked here. Does anyone know if that would be an option? Thanks.

You would need a DPCD emulator to override that

I wouldn’t even know where to start here. I’ve barely found usable EDID emulators for DP…

Thanks again.

Hi PVVC,
I don’t think we have a device that would block the DSC function. I think this setup might be possible but hard to establish. I think if you start with lower resolutions 4k60Hz and then shut down the system, turn off the power to the devices and then turn it back on, it should allow you to set the 120Hz on one screen and then repeat the process for the rest.I think you should get 4k120Hz on all of them. You could also try setting the max refresh rate on the monitor to 120Hz if there is an option.

Hello, thanks a lot. I will try that once I get my system back from the pc vendor (who is currently testing the system).

I agree with you that anything else (emulator, adapters, …) will not really get me anywhere in the end. As soon as there are resolution changes (which are bound to happen when starting/stopping a programm, switching between full screen and windowed, Alt-Tab,…) the problems are guaranteed to occur.

I will also ask MSI one more time, if they couldn’t just provide me with a firmware that allows me to disable DSC, as that would solve all my problems. It can’t be that hard (I wouldn’t even need anything fancy like in the menu, simply fixed off in the firmware version would do the trick). But I can’t do more than ask. An end user is very powerless in the end, if one doesn’t get a lot of support or attraction from the media.