A PC that shuts down without warning — not a crash to a blue screen, but a hard power-off — is one of the more alarming failure modes. The good news is there are a limited number of causes, and each has a systematic test.
Cause 1: Thermal Shutdown (Most Common)
When a CPU or GPU hits its maximum safe temperature, the system powers off instantly to prevent damage. This is the single most common cause of unexpected shutdowns in Nigeria.
Test: Install HWiNFO64 and watch temperatures under load. If CPU or GPU hits 90°C+ before shutdown, thermal shutdown is your culprit.
Fix: Clean dust, reapply thermal paste, improve case airflow, or upgrade your cooler.
Cause 2: PSU Failure or Overload
A PSU that can't deliver its rated wattage — due to age, heat damage, or being undersized — will drop voltage under load and cut power. High-performance components drawing near the PSU's limit trigger this.
Test: Try running with reduced load (remove a GPU, test with onboard graphics). If shutdowns stop, PSU capacity or quality is suspect.
Fix: Replace with a quality 80+ Gold PSU sized appropriately for your system.
Cause 3: RAM Instability
Faulty or incompatible RAM can cause hard shutdowns under memory-intensive load. This often looks similar to a crash but without a BSOD.
Test: Run MemTest86 (bootable USB) for a full pass. Any errors confirm RAM as the issue. Try one stick at a time to isolate the faulty module.
Fix: Replace faulty RAM stick with a verified-compatible module.
Cause 4: Power Quality Issues
In Nigeria, voltage fluctuations and power outages are common. A sudden voltage sag or microsurge can trigger an immediate shutdown. An AVR (automatic voltage regulator) + UPS is the solution — they maintain stable power delivery to the PC regardless of grid quality.