B580 HDR issue in DIY Monitor

[Mr_Tadokoro]

I am encountering an issue with my Intel B580 GPU when using a DIY display setup. The display consists of a panel (AUO B160QAN02.2) and a pass-through board connected via eDP interface. The pass-through board links to the GPU via DisplayPort (DP)

This pannel support 10bit color + 240Hz +HDR. But the GPU only provides a 6-bit depth potion at 240Hz refresh rate. If forcing 10-bit color by Intel Graphics Command Center, the system automatically enables HDR and locks the refresh rate to 60hz, the display exhibits a washed-out/grayish appearance unless HDR is manually enabled.

The same setup works flawlessly with an NVIDIA GPU, it allowing simutaneous 10-bit, HDR, 240Hz refresh rate without issues.

when using a commercially available display, B580 dose not exibit the aforementiones issue and can support 10-bit color with HDR at 240Hz.

[Mr_Tadokoro]

Well, the B580 and AMD 9070XT both support DP 2.1, but the 3060Ti and 4080 Super do not support DP 2.1, it only support DP1.4. Could the HDR grayish appearance on the B580 be linked to DP 2.1 signal handling (e.g., DSC implementation, metadata prioritization) in this DIY setup, whereas NVIDIA’s DP 1.4 path avoids the issue?

I will borrow an RTX 5070 Ti to Verify if the HDR gray issue reproduces under DP 2.1 with this NVIDIA GPU. I will share the RTX 5070 Ti test results once completed.

[MUC]

If the interface implementation of all involved devices complies with the specification, it shouldn't matter that the Arc B580 and the AMD Radeon RX 9070 XT could theoretically support a UHBR13.5 link rate. But never say never...

If you have the opportunity, testing the Nvidia GeForce RTX 5070 Ti would certainly be informative.

[Mr_Tadokoro]

I have tried the iGPU(UHD770), it has the same issue with B580. So it seems that whatever the DP1.4 or DP2.1 is not the root cause.

I have learned to use the CRU and aim to Inject correct HDR static metadata (e.g., min/max luminance values) . Are there recommended CRU settings for Intel GPUS to fix HDR gamma mapping?

[MUC]

CRU is essentially just a graphical user interface and influences the behavior of the graphics driver via the operating system's own EDID override mechanism.

Background information:

• Microsoft Learn > Windows Hardware Developers > Design > Component Guidelines > Display > Display Descriptors
• Microsoft Learn > Windows > Drivers > Display > Monitor EDID Overrides

Your monitor's EDID already contains valid and plausible information:

Color Characteristics

    Red: 0.6611 | 0.3300

    Green: 0.2832 | 0.6171

    Blue: 0.1425 | 0.0537

    White: 0.3134 | 0.3291

---------------

HDR Static Metadata

Electro optical transfer functions:

• Traditional gamma - SDR luminance range
• SMPTE ST2084

Supported static metadata descriptors: Static metadata type 1

• Desired content max luminance: 107 (507.620 cd/m²)
• Desired content max frame-average luminance: 107 (507.620 cd/m²)
• Desired content min luminance: 71 (0.394 cd/m²)

Bending this data via CRU is essentially the same as creating a Windows color profile with the HDR Calibration App. However, since that doesn't seem to resolve the issue, I don't think we've identified the root cause yet.