If the test fails, ensure to write down the error code and validation code.

Follow the on-screen prompts and respond appropriately to complete the diagnostics.

Use the arrow keys to select Diagnostics and press Enter key on the keyboard.

When the Dell logo appears, press F12 key to enter One-time Boot Menu.

Running Dell Pre-boot System Assessment or enhanced Preboot System Assessment (Dell PSA or ePSA) To learn more about Dell ePSA or PSA diagnostics, browse to the Dell knowledge base article Resolve Hardware Issues with Built-in and Online Diagnostics (ePSA or PSA Error Codes). Dell SupportAssist or ePSA hardware diagnostic test help check if the hardware devices are working correctly. Dell offers both integrated and online diagnostics. To determine if your Dell computer is experiencing a hardware problem, it is recommended that you first run a hardware diagnostic test on your computer. Running a hardware diagnostic test can help you identify hardware-related problems and provide you troubleshooting steps to help resolve the issue.

Laptop computers may also have more than one fan and may vary between different models.

Desktop computers have more than one fan - processor (CPU), dedicated or discreet video card (GPU), power supply (PSU), and one or more chassis (case) fans.

Your Dell computer may contain several fans to keep the internal components cool: Lint and dust accumulation prevents air from flowing around the cooling fins and causes the fan to work harder. It is important to keep dust from accumulating in your computer and ensure adequate ventilation to help reduce heat. If you notice the computer fan running constantly and making an abnormal or loud noise, this might indicate that the computer is not running as efficiently as possible, and/or clogged air vents. Excessive heat can also cause a significant decrease in performance as most processors automatically reduce the speed of the processor to help compensate for heat-related problems. Blocked air vents can cause serious performance issues by restricting airflow, this can cause the processor, system memory (RAM), and other hardware to overheat which may lead to a potential hardware failure.

Dell bios fan control