iATKOS | United Kingdom

SOLUTION

Problem: iMac (2010) with NVIDIA Quadro K2100M boots High Sierra normally but fails on macOS 11–15 (Big Sur to Sequoia). Symptoms include boot chime, black screen, maxed fans, unresponsive keyboard, and requires repeated NVRAM resets to boot.

Cause:

• Unsupported NVIDIA GPU: macOS Big Sur and newer lack native drivers for Kepler GPUs (like Quadro K2100M).

• Boot Process Corruption: macOS 11+ uses a modern boot architecture incompatible with legacy NVIDIA hardware.

• NVRAM/GPU Firmware Issues: Inconsistent initialization of the GPU during boot.

Solution Guide

Step 1: Replace GPU with a macOS-Compatible Model

Why?
The Quadro K2100M is not supported in macOS 11+. Use an AMD GPU (officially supported up to macOS Monterey/Ventura) or Metal-compatible NVIDIA card.

Recommended GPUs for iMac 2010:

• AMD Radeon HD 7950/7970M (MXM-III-B, natively supported up to macOS Monterey).

• AMD Radeon Pro WX 4130 (Metal support, works with OCLP in newer macOS).

Procedure:

1. Purchase a compatible GPU (ensure it’s MXM-III-B type).

2. Follow an iMac 2010 GPU replacement guide (e.g., iFixit).

3. After installation, reinstall macOS Sequoia.

Step 2: Use OpenCore Legacy Patcher (OCLP) for Software Fix

If GPU replacement isn’t feasible, use OCLP to patch macOS for Kepler GPU support.

A. Prepare Tools:

1. On High Sierra:

   • Download OpenCore Legacy Patcher (OCLP).

   • Use a 16GB+ USB drive.

B. Patch macOS Sequoia:

1. Build a Patched Installer:

   • Open OCLP → "Create macOS Installer" → Download Sequoia.

   • Select your USB drive → "Build and Install OpenCore".

   • Important: Under Settings → SMBIOS, select iMac13,1 or iMac14,2 (better Kepler support).

2. Install macOS Sequoia:

   • Boot from USB (hold Option at startup).

   • Install macOS on a dedicated APFS volume (do not overwrite High Sierra).

3. Install OpenCore to Internal Drive:

   • After installation, boot back into USB.

   • Select your new Sequoia volume.

   • Once in macOS, open OCLP → "Build and Install OpenCore" → "Install to Disk" (choose internal SSD).

4. Apply Root Patches:

   • In OCLP → "Post-Install Root Patch" → "Start Root Patching" (installs Kepler GPU drivers).

   • Reboot.

C. Configure Boot Args (Critical):

1. Open OCLP → "Post-Install Root Patch" → "Advanced Settings".

2. Add these boot arguments:

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   -wegnoegpu agdpmod=pikera -no_compat_check nvda_drv=1

   (Forces GPU initialization, disables compatibility checks, and loads NVIDIA drivers.)

3. Rebuild OpenCore and reinstall to disk.

Step 3: Reset Firmware and NVRAM

1. Reset SMC:

   • Shut down → Unplug power cable → Wait 15 seconds → Plug in → Wait 5 seconds → Power on.

2. Reset NVRAM:

   • Shut down → Power on → Immediately hold Cmd + Option + P + R until the second chime.

Step 4: Disable macOS Firmware Updates

Prevent macOS from installing incompatible firmware:

1. In Sequoia (once booted):

   • Run Terminal:

     bash

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     sudo firmwarepasswd -setpasswd

   • Set a password to block firmware updates.

Step 5: Verify Boot Disk Settings

1. In System Settings → General → Startup Disk:

   • Explicitly select the Sequoia volume.

2. In OCLP Boot Picker (during startup):

   • Select Sequoia manually each time to avoid automatic fallback to High Sierra.

Troubleshooting

• If patched macOS still fails to boot:

  • Boot in Verbose Mode (hold Cmd + V at startup) to identify hang points.

  • Try Safe Mode (hold Shift) to isolate GPU drivers.

• If fans still max out:

  • Reseat the Quadro K2100M and clean heat sinks (overheating triggers failsafe).

• Last Resort:

  • Use macOS Monterey (last with partial Kepler support) via OCLP for better stability.

Final Notes

• GPU replacement is the most reliable fix—Sequoia will deprecate Kepler GPUs entirely.

• OCLP patches are temporary and may break with macOS updates.

• Backup data before major hardware/software changes!

Success depends on GPU compatibility. If issues persist, consider downgrading to macOS Monterey/Catalina for daily use. 🛠️