PC sometimes stuck at VGA initialization at boot before posting; white underline shown on screen

Title: Diagnosing and Resolving Intermittent VGA Initialization Failures During PC Boot

Introduction

Encountering boot issues can be frustrating, especially when your PC fails to complete the POST process, leaving you staring at a blank screen with a white underline and an error indicator pointing to the VGA subsystem. Such problems, while sometimes intermittent, can be caused by a variety of hardware or settings-related factors. In this article, we’ll explore a real-world scenario of a PC exhibiting intermittent VGA initialization failure, review troubleshooting steps, and offer professional advice on how to address this issue effectively.

Understanding the Problem

The user reports that upon rebooting or powering on, the PC occasionally fails to POST, with the debug LEDs indicating a VGA-related fault. The display shows only a white horizontal underline—similar to a brief flicker seen during normal startup before the BIOS logo appears. Notably, this occurs before any BIOS beeps are emitted.

Common Symptoms:
– Intermittent failure to POST
– VGA debug LED status during failure
– Brief appearance of a white underline on the monitor
– Requires manual intervention to resolve

Initial Attempts at Resolution

The user initially attempted basic troubleshooting:
– Reseating GPU and power cables, with no physical damage detected
– Resetting CMOS settings, which temporarily fixed the issue
– Swapping the power supply from an aging Seasonic Prime 650W to a new be quiet! 850W PSU, which temporarily resolved the problem for about a week

Further Observations

Despite these efforts, the problem re-emerged and even worsened over time. Power cycling the PSU or unplugging/replugging doesn’t consistently resolve the issue; resetting CMOS appears to help temporarily. Notably, hardware modifications like installing a PCIe to M.2 adapter and switching to Linux were performed after the issues had already begun, though these are unlikely to be the root cause given the symptoms.

Potential Causes and Diagnostic Considerations

1. Hardware Degradation or Compatibility:
2. The PC is approximately 7-8 years old, and components like the GPU and motherboard may be aging.

3. The new PSU reduces power stability issues but may not eliminate hardware aging effects.

4. Graphics Card Issues:

5. The GPU is relatively new and functions correctly once the system POSTs.

6. Intermittent VGA boot failure could indicate GPU socket contact issues, although reseating suggests physical connection is adequate.

7. Motherboard or BIOS Settings:

8. BIOS