I want to warn at once: the photo is not for the faint of heart :)
I worked one year in one company. Computers were about 7 years old, during this time no one was cleaning them. For this year I cleaned up all of them. I saved some hardware, but something had to be thrown away.
When people ask me: "why does my computer slow down?", I show these photos.
Dust on the processor is like a small metropolis. Capasitors will soon grow in moss.
Is this a power supply unit?
For this I want to tear off your hands. So you can not use the technique!
Finally, the keyboard. It seems that it too has not been cleaned for 7 years. The food deposits are huge. It's a black copy, it does not even show dirt on it, just crumbs.
People, this is cry of my soul. Please appreciate your technique, clean it regularly and it will serve you a long time!