Here are some of the most common causes of logic board malfunctions in iMacs.
Liquid damage
Liquid spilling is something that is very common in workplaces and households. When liquid gets inside of a computer, it is only a matter of time before it reaches the logic board. Because the insides of a computer are very prone to corrosion at the slightest bit of exposure to moisture, there is a high chance that the seeping of water or any other liquid inside the computer would wreak havoc on the internal components. In this case, the first thing you should do is disconnect the computer from its power source and get it sent to our service centre for a deep clean. Under no circumstances should you try to open the computer by yourself and try to get it working again. That can be dangerous due to the involvement of several high-powered components inside the hardware.
Overheating
In general, overheating for every computer is bad. All parts of the computer need efficient cooling and a range of optimal temperatures for them to run at their maximum efficiency. The CPU and the video card of the computer often draw a lot of computing power from the logic board and generate heat. If this heat is not efficiently dissipated by the computer, it is only a matter of time before the computer begins to thermal throttle and grind to a halt. Over time, repeated.