My computer powers on, (case lights/fans turn on, cpu fan spins, harddrive makes sounds) but doesn't boot (my usb mouse doesn't light up, monitor doesn't recieve signal). However, when I press down on my cpu fan, pushing it towards the mobo gently, it works. But then, the computer freezes up after about 20 or 30 minutes randomly. Any ideas? Sorry if I missed something I'm a first time poster.