Post not exactly clear, so fans stops spinning, so system still boots up? getting a Windows Logo?
If system can't boot up for whatever reason, it could had simply shut down, and off the fan with it. So the question is, the chicken or the egg. I suspect more power related. U gotta give us more info/history than that scant post. Doctors are no magicians without patient disclosing what's wrong. Electronics typically don't all of a sudden die, something happened to it.