Fixing No Signal Issue on Radeon HD 7870 in macOS Sierra and Later

Guide:

Introduction

If you're encountering a "No Signal" issue when using DVI on your Radeon HD 7870 in macOS Sierra or later, and you want to use your DVI monitor instead of Mini DisplayPort, you may need to adjust your graphics settings. Here's a guide to help you resolve this issue.

Troubleshooting Steps

1. Check Monitor and Cable:

   • Ensure that your DVI monitor and DVI cable are functioning correctly. Try using a different DVI cable or testing your monitor with another computer to rule out hardware issues.

2. Graphics Injection:

   • Open your config.plist and check if you have any graphics injection properties or settings for your Radeon HD 7870. If present, try removing or adjusting them.

3. Framebuffer Patching:

   • Consider framebuffer patching using tools like Hackintool or WhateverGreen.kext to ensure that the correct framebuffer is used for your graphics card. This may require experimentation to find the right settings.

4. Boot Arguments:

   • Experiment with different boot arguments related to graphics. Some common ones to try include "radpg=15" or "GraphicsEnabler=Yes/No."

5. Try Different Ports:

   • If your Radeon HD 7870 has multiple DVI ports, try different DVI ports on the graphics card. Sometimes, one of the ports may work better with macOS.

6. macOS Version Compatibility:

   • Ensure that your macOS version (Sierra) is compatible with your Radeon HD 7870 graphics card. Some macOS versions may have limited support for older graphics cards.

7. Graphics Kexts and Drivers:

   • Check that you have the appropriate graphics kexts and drivers installed for your Radeon HD 7870. Update them if necessary to ensure compatibility with macOS Sierra.

8. Legacy GPU Considerations:

   • Being a legacy system with no UEFI support, you might need to explore specific configurations and patches for legacy GPUs like the Radeon HD 7870. This may involve trial and error to find the optimal settings.

9. Community Support:

   • Seek assistance from the Hackintosh community or forums, as users with similar legacy hardware setups may have encountered and resolved this issue. They can provide specific guidance and solutions.

10. Backup and Experimentation:

    • Before making any significant changes, back up your current configuration. Experiment with different settings, but keep track of changes, so you can revert if needed.

Conclusion

Resolving the "No Signal" issue on your Radeon HD 7870 for DVI output in macOS Sierra or later can be challenging due to legacy hardware and limited compatibility. However, by following these troubleshooting steps and seeking support from the Hackintosh community, you may find a solution that allows you to use DVI with your monitor.

Always ensure you comply with legal and ethical guidelines when using macOS on non-Apple hardware, and remember to back up your data and configurations before making any major changes to your system.