[Help] Second monitor loses signal after Windows boots (DisplayPort issue, HDMI works fine)

Understanding and Troubleshooting DisplayPort Connectivity Issues on Your PC

If you’ve recently added a second monitor to your PC and are experiencing an unusual issue where the monitor connected via DisplayPort loses signal after Windows boots, you’re not alone. This problem, while perplexing, can often be traced to hardware configurations, driver settings, or compatibility concerns. Below, we delve into what might be causing this issue and outline steps to diagnose and resolve it effectively.

Overview of the Issue

In this scenario, the user has a Radeon RX 6600 XT graphics card with three DisplayPort outputs and one HDMI output. The primary monitor is connected via HDMI and functions correctly. The secondary monitor, connected through DisplayPort, displays the BIOS screen and Windows boot logo. However, once Windows fully loads, the monitor loses signal and turns off, despite seemingly being recognized during startup. Interestingly, switching the monitor to the HDMI port results in proper display, indicating the monitor and cables are functional.

Key Observations:
– The secondary monitor works during BIOS and Windows boot logo stages.
– Post-Windows load, the monitor connected through DisplayPort loses signal.
– Windows Display Settings do not detect the second monitor after boot.
– Using the same monitor and cable on the HDMI port works flawlessly.
– Uninstalling and reinstalling GPU drivers changes behavior, with the DisplayPort-connected monitor sometimes working after driver removal.

Troubleshooting Steps and Recommendations

1. Verify Cable and Monitor Compatibility
   Ensure that the DisplayPort cable is certified and functioning correctly by testing with another monitor or cable. Although initial tests suggest the hardware is fine, confirm there are no compatibility issues.

2. Check Graphics Card and Driver Settings

3. Update to the latest GPU drivers from AMD to ensure compatibility and fix known bugs.
4. Use AMD’s Radeon Software to configure display settings, and verify that multi-monitor setups are correctly recognized.

5. Consider rolling back to an earlier driver version if the issue started after a recent update.

6. Assess BIOS and UEFI Settings

7. Review BIOS/UEFI settings for any display-specific options—such as Primary Display or HDMI/DisplayPort priorities—that might influence signal routing.

8. Ensure that the PCIe slots and display outputs are enabled and configured correctly.

9. Test Different Ports and Cables

10. Connect the secondary monitor to different DisplayPort outputs (if available) to rule out port-specific issues.

11. Use a different, high-quality DisplayPort cable to eliminate cable faults.

12. Evaluate Windows Display Configuration

13. After Windows loads