My computer keeps shutting itself off after progressively slowing down over a few minutes.

Troubleshooting a Sudden, Progressive Shutdown Issue on Your PC

Experiencing unexpected shutdowns or system failures can be a frustrating ordeal, especially when your computer’s performance gradually deteriorates over a short period. If your PC is shutting down unexpectedly after a brief slowdown — even after taking preventive measures like dusting and thermal paste replacement — it’s essential to systematically diagnose the underlying cause. Here’s a comprehensive guide to help you identify and resolve such issues.

Understanding the Symptomatology

In cases where a computer initially boots normally but begins to slow down over a few minutes before shutting off, common culprits include hardware overheating, power supply issues, or component failures. The fact that your system sometimes displays boot errors or powers off shortly after starting adds to the suspicion of hardware instability.

Steps You’ve Already Taken

Powering down and unplugging the PC before leaving helps prevent hardware degradation during extended disuse.
Cleaning the interior components, including dust removal, improves airflow and cooling.
Replacing thermal paste can enhance CPU thermal performance.
Testing with a different power cord rules out a faulty external power source.

Despite these steps, the problem persists, indicating that further diagnostics are necessary.

Potential Causes and Diagnostic Strategies

1. Overheating Components

You’ve observed increased heat behind your CPU on the motherboard, which could signify overheating.

Check CPU and motherboard temperatures using hardware monitoring tools (like HWMonitor or Core Temp) immediately after booting and during load conditions.
Inspect cooling solutions: ensure fans are operational, heatsinks are properly seated, and airflow is unimpeded.
Evaluate thermal performance: even with new thermal paste, heat issues can persist due to faulty fans or blocked airflow.

Tip: If components regularly reach high temperatures, consider upgrading cooling solutions.

2. Power Supply or Power Delivery Problems

Unstable or insufficient power can cause shutdowns, particularly if components are drawing more current due to thermal or hardware issues.

Test with a known-good power supply if available.
Check system power settings and ensure the PSU’s wattage capacity surpasses your system’s requirements.
Monitor voltage outputs via BIOS or hardware monitoring software if your motherboard supports it.