What should you check if your PC does not start after replacing the motherboard?

When troubleshooting a PC that does not start after replacing the motherboard, checking the power button connection to the motherboard is crucial. The power button, usually connected via a front panel header, activates the power supply to start the system. If this connection is loose or improperly installed, the motherboard will not receive the signal to power on. Therefore, ensuring that the power button is correctly connected is an essential first step in diagnosing the issue after a motherboard replacement.

While ensuring the RAM is properly seated is an important step in general when dealing with hardware issues, it is not the first action to take specifically related to a motherboard replacement. If the RAM was functioning properly before the motherboard swap, it typically will still be, unless it was inadvertently disturbed during installation. Replacing the power supply unit might not be necessary unless there are signs of power issues, making it an unnecessary step at this stage of troubleshooting. Similarly, updating the BIOS is usually not the first action; it typically follows after ensuring all physical connections and basic hardware are functional. Thus, verifying the power button connection directly addresses a likely point of failure immediately following a motherboard change.