Troubleshooting Motherboards, RAM, CPUs & Power | CompTIA A+ 220-1001 | 5.2

In this video you will learn about troubleshooting problems related to motherboards, RAM, CPUs, and power.

Common Symptoms

Unexpected Shutdowns

Typical causes for unexpected shutdowns include the following:

  • Dead electric shorts: Make sure everything is secure & properly seated.
  • CPU overheating:  Check fan speed & clean if it is dirty; replace fan if it has failed or is turning too slowly.
  • Power supply overheating:  Clean the power supply or replace the power supply with a higher wattage-rated unit if necessary.
  • Power supply failure:  Test the power supply to verify proper operation.

System Lockups

A system lockup (also known as a “hang” or “freeze”) occurs when either a process or system ceases to respond to inputs. A typical example is when a computer’s GUI no longer responds to the user typing on the keyboard or moving the mouse. System lockups are typically caused by the corruption of memory contents.

To diagnose a system lockup:

  1. Shut down the system, remove and install memory, and remove dust from the modules, the sockets, cooling vents, and fans.  If the problem persists, memory might be overheating.
  2. Check the specifications to make sure you have the proper memory installed for the CPU or motherboard.
  3. If memory has been overclocked, reset the memory to factory specifications. Overclocking generates excess heat, which can cause damage to components.
  4. Add additional system cooling.

POST Code Beeps

POST stands for “power on self-test”. The computer POST checks a computer’s internal hardware for compatibility and connection before starting the remainder of the boot process. If the computer passes the POST, the computer may give a single beep (some computers may beep twice, some computers blink lights) as it starts and continues to boot. However, if the computer fails the POST, the computer doesn’t beep or generates a beep code telling the user the source of the problem. Beep codes vary by the BIOS maker. Check the documentation for the system or motherboard to determine if beeping, blinking, or other reporting methods are used to indicate POST problems. Also understand that beep codes can only be heard on systems with built-in speakers.

Common System Errors & Their Beep Codes

Blank Screen on Bootup

A blank screen on bootup can be caused by a variety of video configurations or cabling problems, some of which can be caused by motherboard issues:

  • Inactive video port on a system will cause a blank screen. Be sure to plug display into an active video port.
  • If a display with 2 or more inputs is not configured to use the correct cable, the display will be blank.
  • Make sure all cables (DVI, VGA, HDMI, miniHDMI, DisplayPort, miniDP) are properly secure.
  • If all of the cables and display input settings are correct but there still isn’t any image displaying on the screen then simply replace the entire display assembly. LCD & LED display modules for laptops and desktops are way cheaper today than they used to be some years ago. There really is no need to open up a display to fix an inverter on an LCD-CCFL or an LED driver board. Just simply replace the display unit.

BIOS Time & Settings Resets

BIOS time and settings reset issues are typically caused by either the CMOS battery on the motherboard or the CMOS chip. If date and time settings or other BIOS settings reset to system defaults or display CMOS corrupted errors, replace the CMOS battery and reset the BIOS settings to correct values. If the CMOS chip on the motherboard is damaged, then the entire motherboard must be replaced. If other settings, such as BIOS passwords, have been lost or corrupted, the CMOS contents can be cleared by using a jumper on the motherboard. See the motherboard/system documentation for details about jumper location & how to properly use it for that particular motherboard.

CMOS Jumper

Attempts to Boot to Incorrect Device

In the BIOS settings, the boot sequence determines which drives can be used to start a computer & in what order. Non-bootable drives in the boot sequence will prevent the system from starting. For example, if a USB drive is listed first, and a non-bootable USB drive is plugged in, the system will not start. To remedy this, change the boot order to display the location where the operating system is installed (system hard drive) & then reboot the computer.

Continuous Reboots

Hardware failures or system instability can cause a computer to reboot continuously. The problem could be the RAM, hard drive, power supply, graphics card, some external device, or an overheating BIOS issue. Ways to mitigate this problem are as follows:

  • Apply troubleshooting in Safe Mode
  • Disable the Automatically Restart feature
  • Disable fast startup
  • Uninstall latest installed apps
  • Uninstall latest Windows updates
  • Update system drivers
  • Reset Windows to the earlier System Restore point
  • Scan your system for malware
  • Check for hardware issues
  • Check external devices to see if any of them are causing the restart issues

No Power

No power to the system can be caused by several issues such as:

  • Power supply failure: Use a multimeter or a power supply tester to determine if a power supply has failed.
  • Incorrect front panel wiring connections to motherboard: Check the markings on the front panel connectors, the motherboard, or the motherboard/system manual to determine the correct pinouts and installation.
  • Loose or missing power leads from power supply: Make sure the power leads from the power supply are connected firmly to the motherboard.  The connectors lock into place.
  • Surge suppressor or UPS failure: Replace the defective surge suppressor or UPS unit or replace the battery in the UPS unit.


Overheated power supplies can cause system failure and possible component damage, and they can be due to any of the following causes:

  • Overloading: An overloaded power supply is caused by connecting devices that draw more power (in watts) than the power supply is designed to handle.
  • Fan failure: The fan or fans inside the power supply cool it and are partly responsible for cooling the rest of the computer.  If fans fail, the power supply and the entire computer are at risk of damage. Replace fans if necessary (see manufacturer’s instructions).
  • Inadequate airflow outside the system: If the computer is kept in a confined area without adequate ventilation, power supply failures due to overheating are likely.
  • Inadequate airflow inside the system: Use cable ties to secure excess ribbon cable and power connectors out of the way of the fans and the power supply. Make sure the case fans and CPU fans are working correctly.
  • Dirt and dust: Use a vacuum cleaner specially designed for computer use or compressed air to remove dirt and dust from inside the system.

Loud Noise

Computers are designed to usually run quietly with a low hum. Loud noises could be an indicator of quite a few issues that you need to check on immediately.

  • Screeching, rattling, or thumping noises indicates that there is probably an issue with your fans.
  • Grinding noises could indicate that there may be loose connections inside of your computer case.
  • Scraping or clicking noises could indicate that there may be an issue with your hard disk drive. Be sure to backup all of your data if this is the problem.

Intermittent Device Failure

Intermittent failures of USB bus-powered devices usually happen because the devices draw power from the system’s power supply via the USB port.  These types of failures, especially for devices with low power draws such as mice and keyboards, can be an early sign of an overloaded power supply.  In that case, you would need to replace the power supply with a higher-rated unit. Other intermittent failure issues by way of USB devices or internal devices could be due to damaged cables, connectors, or ports.

To troubleshoot these problems:

  1. Turn off device & replace the data cable with a working replacement.
  2. Turn on the device or computer.
  3. Test the device.  If the device works correctly, the problem is solved.
  4. If Step 1-3 didn’t resolve the problem, use the original data cable and try plugging it into a different internal or external port.  Repeat steps 2-3.
  5. Try steps 1-4 again, but this time use a replacement power connector or AC adapter.
  6. When you find the defective component, the problem stops.  If the problem is not resolved with different data cables, connectors, or power supplies/AC adapters, the device itself needs to be replaced.

Fans Spin — No Power to Other Devices

If a fan spins and a computer never displays any startup messages, check the following:

  • Make sure the main ATX and 12V ATX or EPS power leads are securely connected to the appropriate sockets.
  • Make sure the CPU and memory modules are securely installed in the appropriate sockets.

Indicator Lights

An indicator lis a light or LED that prompts the user to the status of a hardware device and these lights are usually located on the front or top of most desktop computers. If these lights go out but the system is still working properly, check the indicator lights’ motherboard connection.

Smoke or Burning Smells

The sight and/or smell of smoke means that your computer has serious issues with its hardware and you need to unplug the computer from its power source immediately. If you can see smoke or smell a burning odor with a chemical overtone coming from the power supply’s outside vent, your power supply has died.  When a power supply blows up like this, it can also destroy the motherboard, bus-powered USB devices connected to the computer, and other components. 

Proprietary Crash Screens (BSOD/Pin Wheel)

Proprietary crash screens such as the Windows STOP error (blue screen of death, or BSOD) or the macOS pin wheel can be caused by operating system, application, or hardware errors. STOP errors can occur either during startup or after a system is running.  Regardless of when a STOP/BSOD error occurs, the system is halted by default.  If the computer does not restart on its own, you must turn off the system and turn it back on.  But before you do that, record the error message text and other information so that you can research the problem if it reoccurs.

Distended Capacitors

A capacitor is a component made of two or sets of two conductive plates with a thin insulator between them and wrapped in a ceramic and plastic container. When the capacitor receives a DC (direct current), a positive charge builds up on the plate (or set of plates) while a negative charge builds up on the other. Capacitors are used as part of the voltage step-down circuits that provide power to the processor. A distended capacitor is what happens to a capacitor when it fails and the flat top bulges out indicating failure. Distended capacitors can cause system failures and sometimes physical damage to the motherboard.

Distended Capacitors

Log Entries & Error Messages

A computer log is a detailed list of application information, system performance, or user activities. A log can be useful for keeping track of computer use, emergency recovery, and application improvement. To access logs and error messages, go to Control Panel > Administrative Tools > Event Viewer.

Windows Event Viewer