My laptop turn off automatically

Hello,

I have Hp Compaq Nx9110 laptop. When i turn on after 4 or 6 second it automatically shutdown but sometimes it load windows then it shutdown. I minimize some devices like harddisk, cdrom just i put ram processor so again the same problem occur. There is one point when i take out ram then it does not shutdown i also clean its heat sink but nothing happen is there anyone can help me.
thanks