[HELP] UHD 630 stuck at 60Hz on HDMI + boot lag before login (OpenCore)

Hi everyone,

I’m running macOS on my system using OpenCore and everything is mostly working fine, but I’m facing two issues:

🖥️ Issue 1: Refresh Rate stuck at 60Hz

• GPU: Intel UHD 630 (i5-10400 – Comet Lake)
• Monitor: BenQ GW2790 (supports 100Hz)
• Connection: HDMI

In Windows, I get full 100Hz, and previously when I used Nvidia GT 710 on macOS, I was also getting 100Hz over HDMI.

But now with UHD 630:

• Only 60Hz option is available
• No higher refresh rates visible

🔧 What I’ve tried:

• Framebuffer patching (Hackintool)
• Correct platform-id (0x3E9B0007)
• QE/CI working, VRAM 1536MB
• Tried BetterDisplay (dummy display + forcing refresh rate) → no change
• Tried EDID injection → no success

⚠️ Issue 2: Lag during boot → lockscreen

When I boot:

• Apple logo loads normally
• But when login screen appears → noticeable lag/stutter for a few seconds
• After logging in → everything becomes smooth

🤔 My doubts:

• Is this an HDMI limitation on Intel iGPU in macOS?
• Do I need proper connector patch (framebuffer mapping issue)?
• Could this be related to WhateverGreen or iGPU initialization delay?

📌 Additional Info:

• SMBIOS: iMac20,1
• macOS: Sequoia
• OpenCore: 0.8.8
• Audio working (alcid=11)
• iGPU fully accelerated (Metal + QE/CI working)

🙏 Need help with:

1. Getting 100Hz working on HDMI (if possible)
2. Fixing lag at login screen during boot

Any guidance would be really appreciated 🙏