PC acting strangely, wouldn’t post for a minute before, booted up, two days later acting strangely and won’t turn back on.

Understanding and Troubleshooting Unusual PC Behavior: A Guide for Enthusiasts

Encountering unexpected issues with your personal computer can be both frustrating and perplexing. Recently, a user shared their experience of a desktop behaving erratically, which offers valuable insights into diagnosing common hardware problems. Below is a detailed account of the situation, along with potential troubleshooting steps and considerations.

Case Overview

Initial Symptoms:
– During routine operation, while attempting to alt-tab from a repository, the display rapidly flickered—alternating between black screens and faint visuals—suggesting potential video signal disruptions.
– Following a shutdown, the PC experienced difficulty booting up, with delays of several minutes before starting. Eventually, the system returned to normal functioning.

Progressive Issues:
– Two days later, the user attempted to sign in, but the keyboard remained unresponsive.
– When trying to access Windows shutdown options, the menu failed to appear.
– Subsequently, a forced shutdown was performed, after which the computer refused to power on once again.

Potential Causes and Troubleshooting

Memory (RAM) Inspection
Faulty or improperly seated RAM modules can cause boot issues and unpredictable behavior.
Action: Check the RAM modules—ensure they are securely seated. Run memory diagnostics (such as Windows Memory Diagnostic or MemTest86) to identify possible defects.
Power Supply Integrity
The user’s setup includes a used Corsair 850W PSU. Used power supplies may have degraded components impacting stability.
Symptoms like failure to turn on or sudden shutdowns could originate from insufficient or unstable power delivery.
Action: Test the system with a known-good, possibly new, power supply if available. Monitor voltages and overall power stability.
Graphics Card Considerations
The RTX 3080, acquired used, has not previously exhibited issues, but GPU problems can lead to display flickering and boot struggles.
Action: Check video connections, reseat the GPU, and consider testing with integrated graphics or another GPU if possible.
Other Hardware Checks
Verify all connections, including power cables and data connectors.
Inspect for signs of physical damage or dust accumulation.
Update BIOS/firmware to ensure system compatibility and stability.
System Diagnostics and Monitoring
Use system monitoring tools to observe temperature, voltages, and CPU/GPU activity.
Conduct a clean boot to