The motherboard is the most expensive and technically complex component of a laptop. It is its malfunction that most often forces the user to choose: repair or buy a new one. Understanding that the problem is really in the board and not in another component is already half the solution.
Symptoms of a motherboard failure
Problems with the motherboard rarely manifest themselves clearly. Most often, the symptoms are indirect and can be disguised as other malfunctions.
The laptop does not turn on at all - there is no reaction either to the power button or to the charging connection. In this case, the charging itself is working properly (the indicator is on, the voltage is normal). This could be a faulty power controller on the board or a broken mosfet.
The laptop turns on, but there is no image - the fan is spinning, the indicators are blinking, but the screen is black even when an external monitor is connected. There is likely a problem with the north bridge or video chip, which is soldered on the board.
Random shutdowns and reboots for no apparent reason, artifacts on the screen (color stripes, pixel spots), unstable operation of USB ports or sound - all this can also indicate the board.
How to distinguish a board problem from other components
Before drawing conclusions, you need to rule out other causes. Laptop won't turn on - first check the battery and charger with a multimeter. There is no image - try connecting an external monitor via HDMI: if a picture appears, the problem is in the screen or cable, and not in the board.
Random shutdowns - first check the temperature under load: the cooling system may simply be clogged. If after cleaning and replacing the thermal paste the problem remains, look further.
Motherboard diagrams for most popular models from Lenovo, ASUS, Acer, HP and Dell can be found at electronics repair motherboard diagrams - this greatly simplifies the diagnosis of specific power circuits and components.
Typical malfunctions and their causes
The most common reason for board failure is liquid ingress. Even a small amount of water or tea spilled on the keyboard will penetrate and cause corrosion or short circuit on the circuit board. In this case, the laptop can work for several more days after liquid contact - until oxidation spreads to critical elements.
The second reason is mechanical damage. Impacts, falls, and deformation of the case can lead to microcracks in the soldering or damage to the tracks.
The third is degradation of the video chip or bridge due to constant overheating. This is especially true for laptops from 2008–2014 with discrete graphics from NVIDIA 8xxx–9xxx series and some AMD:
