Why does dust make a computer shut down?

The dust could be a conductive, and your computer chip is being compromised.
The dust is probably just overheating the board. Unplug your computer, open it up, and vaccuum the damn thing.

The dust blocks proper airflow through the vents and fans inside your computer. Without proper airflow, the internal components overheat and shut down. I once opened my case to clean it out and I swear I got a whole cat out of there.

You really should open it up every couple of months or so and either vacuum it or use canned air to blow the dust out. Do it more frequently if you have pets or if you smoke in your home.

Both @filmfann & @Seelix are correct. Dust is both conductive and can cause components to overheat which throws the computer in a safety mode (shutting down). Also DO NOT USE A VACUUM, using a vacuum creates a lot of static charge. That could then turn nice unharmed components into components that could drastically reduce the life of your system. Please use canned air & non-conductive things to clean it.

Components usually do not shut down due to heat.
A pc mainboard has internal sensors that detect overheating and trigger a shut off command in the BIOS to protect the system from thermal death. (ever seen a burning cpu?)

Sorry, I should have specified about the vacuuming – you can buy vacuums that are specially designed to clean out computer CPU cases. Don’t just use your regular house vacuum.

And sorry for my less-than-expert terminology – by “internal components” I just meant “all that stuff inside the box”.

Haha, I love the music in that video @ragingloli. It’s like old school science class or something, Lurve!

My last PC I built had a sweet sensor (that I placed under the heatsink with the CPU) that connected to a temp gauge on the front the tower case, so I could watch the temperature. Damn, now I want to build another, lol.

You need a bottle of Pledge…..the dust magnet!