The complaint was that the computer kept switching off randomnly. It also was producing artefacts and weird stuff on the screen.
Opening up the box showed the reason. Overheating due to clogged up CPU and power supply cooling system.
Cleaning regularly the cooling components of a computer is extremely important in order to maintain reliability and performance.
It is also very important to maintain the work environment as free as possible from dust and fluff, sometimes a real challenge.
Some desks designed to hide the computer in a closed off cavity are just a very bad idea! Looks neat, but the poor machine needs fresh air to breath! And a way to vent off the hot air. And those closed off cavities are nearly impossible to keep clean.
Note that it is practically impossible to completely ward off the dust and fluff, pet hair, from getting inside the computer. The fans are supposed to suck air in, and the static electricity inside also compounds the problem. However some careful placement choices can make a tremendous difference.
A computer placed off the floor (preferably on the desk) will be less prone to sucking in all the particles floating around on a carpet and under the desk. Periodically cleaning the inside of the machine will require compressed air, brushes and patience. This applies to laptops and all-in-one PCs as well.
Benefits will be stability and reliability, as well as a quieter and cooler system.