The strangest black screen ever.

Hello,

I have the weirdest problem ever, my computer, only after restart (If I shutdown and start this doesn't happen), won't boot, and won't give any signal to monitor, I press power button and all I get is a black screen, fans spinning but nothing more, it is not booting because even if I wait 5 minutes (checking if it was just a monitor problem) when I click the power button it shutdowns instantly. I found out that after a random number of tries it starts up normally, but I would like to solve this problem, one time I had to turn the pc on 50 times or something.