PG42UQ - Stuck at 8-bit colour depth at 138 Hz

[RyanOCallaghan0]

Hi all. 

As the title says, my Asus PG42UQ appears to be stuck at a colour depth of 8bpc when in 138 Hz mode - this is according to the monitor's OSD. In the NVCP I can manually set it to 10 or 12 bit, but regardless of the setting here, the monitor is stuck at 8bpc in the OSD. The issue is not present at 120 Hz. I am using HDMI 2.1. 

As HDR is very important to me I want to ensure I can get the full native 10bpc colour experience - but sacrificing 138 Hz is a significant cost as this was one of the reasons I went for this monitor over a 42" LG C3. 

Is this a limitation by design or could it be corrected with (yet another) firmware update? 

Thanks in advance.

[Silent_Scone]

Hello,

Have you tried DP1.4?

What HDMI cable are you using? Can you confirm it's HDMI 2.1?

This is using the supplied DP 1.4 cable (GPU AMD 7900XTX)

[RyanOCallaghan0]

I have yet to try DP with this monitor, I wanted to use HDMI so I can avoid the need for DSC. 

The cable I am using is a 1.5m HDMI Ultra High Speed certified cable, so yes, it is validated for 48gbps. 

If you insist I can try DP too, but it looks like further improvements are required to the firmware of this monitor - v040 has already come a long way over previous versions though! Cannot speak for the PG48UQ however. 

Thanks

[Silent_Scone]

Try with both cables supplied with the panel.

Within Windows this should ideally be left at auto as it will detect native 10bit content. Try launching a game in HDR10, see if the OSD updates.

[RyanOCallaghan0]

I have indeed been playing HDR10 games with HDR enabled, but the colour depth is stuck at 8bpc using HDMI 2.1 at 138 Hz. Tried the included cable, no changes. 

DP, which I have just tried for the first time with this monitor, does allow for 138 Hz and 10 bpc simultaneously as expected. 

I am using an RTX 4090 so HDMI 2.1 is supported on the GPU side as well. HDMI 2.1 is the higher bandwidth standard so this really should not be the case, and scrolling down the forums a bit, it seems I am not the only  one to have reported this. Please look into it. 

Thanks 

[Silent_Scone]

 

Thanks for testing. Just to confirm - you're on v40 firmware? Also, ensure you're using the HDMI 2.1 ports.

[RyanOCallaghan0]

I am on v040, yes, and I was using HDMI 1 which is right next to the DP port. 

The labelling on the picture you showed seems to have the HDMI 2.1 and USB 3.2 ports mixed up, btw.

Thanks 

[Silent_Scone]

I’m sure you’re able to make that distinction lol. As long as you’re not using the HDMI ports highlight higher up.

I’ve moved the thread to ROG Care, feel free to upload a dxdiagnostics via run>dxdiag  

[bp328i]

Same thing here with v40 set to 138Hz and a HDMI 2.1 cable. It only shows 8 bit while DP will show 10 bit. I'm running a ASUS TUF OC 4090 so it's definitely capable of 10 bit over HDMI 2.1. 

Hopefully it's not a hardware limitation with the PG42UQ and can be correct via firmware.