Skylake HD 520 – HDMI Purple/Magenta Tint in Ventura (Kaby Lake Spoof)

[JuanPerezzzzz]

Hello everyone,

I'm experiencing an HDMI color issue in macOS Ventura using a Skylake HD 520 iGPU with Kaby Lake spoofing. After extensive testing, the problem persists.

Here are the full details.

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💻 System

• Laptop with Intel Skylake HD 520

• macOS Ventura

• OpenCore (latest stable version)

• SMBIOS tested:

  • MacBookPro14,1

  • MacBookPro14,2

• iGPU spoofed as Kaby Lake (required for Ventura)

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🖥️ The Problem

HDMI works and outputs a stable image, but:

• Entire screen has a purple/magenta tint

• White appears greenish

• Colors are clearly incorrect

• Changing color profiles has no effect

System log shows:

 

The color mode = 0x100 is not RGB for DP

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🔍 What the logs show

Framebuffer attempts DP initialization first:

 

Setting DP power state = 1 WriteAUX Timeout ReadAUX Timeout Setting DP power failed (0xe00002bc)

Then it falls back to HDMI, but color mode seems already locked in a non-RGB state.

It appears the Kaby Lake framebuffer is initializing in a DP-like color space (possibly YCbCr) even though the physical port is HDMI/TMDS.

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🧪 What Has Been Tried

✔ Boot arguments tested

• -cdfon

• -agdpmod=ignore

• -igfxhdmi

No change in color behavior.

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✔ Connector patching

• Connectors set as HDMI

• Adjusted busID and pipe values

• Multiple connector configurations tested

HDMI works functionally, but color remains incorrect.

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✔ Manual EDID Override

• Extracted EDID via:

   

  ioreg -lw0 | grep IODisplayEDID

• Converted to Base64

• Created override in:

   

  /Library/Displays/Contents/Resources/Overrides/

• Attempted to force RGB

Result: no change.

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✔ Color profile calibration

Tested advanced calibration and different color profiles.

Result: no impact on the magenta tint.

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📌 Important Detail

This exact hardware works perfectly in macOS Monterey.

The issue only appears in Ventura, where Skylake must be spoofed as Kaby Lake.

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🎯 Working Theory

It seems:

• Kaby Lake framebuffer forces color mode 0x100

• DP initialization fails, then falls back to HDMI

• Color space remains non-RGB

• EDID override is ignored

• HDMI output is locked in incorrect color mode

This looks like a structural incompatibility between:

Real Skylake hardware + Kaby Lake framebuffer spoof + Ventura graphics stack

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❓ Question

Is there any known method to force true RGB output in HDMI under Ventura with Skylake spoof?

Has anyone patched out the color mode 0x100 behavior?

Or is this a known limitation of Skylake on Ventura?

Any insight would be greatly appreciated.

Thank you.

[MaLd0n]

Try this

https://olarila.com/files/Utils/ForceRGBEasy.zip

[JuanPerezzzzz]

Hi MaLd0n,

ForceRGBEasy worked — the purple/magenta tint is completely gone now. HDMI is running in proper RGB 4:4:4 and the image looks correct. Thank you very much.

However, after applying the patch (CEA extension removed), HDMI audio disappeared and no longer shows up as an output device in macOS.

Is there any way to keep forced RGB while also preserving HDMI audio through the same cable?

Thanks again for the help. ❤️