Computer shuts down?

When I start my computer, it will shut down after 10 – 15 seconds. The Monitor wont have a picture, but everything starts up fine. Even the ventilators work proper. What could be the problem???

I am not clear on if you ever seen anything on your screen. If the screen never comes on, it could be your monitor or your graphics card / chip . Again your question is too vague even hazard much of a guess.
Take it to a computer shop.

A broken PC fan controller with a lot of noise