I recently built a computer, had it all in the case and the power button did not work, but i could still turn the computer on by shorting the power pins. I installed windows 8.1 like this when it was in the faulty case. I then returned this case, waited about a week, then put everything in the new case, which would turn on with the power button. But when i boot it up, i just takes me to the BIOS, with no option to boot from hard drive, which is where i have windows 8.1 installed. Please help me if you can.
select your hard drive in the bios and make it the first boot device. See if that allows you to boot off of it. This also assumes you have the SATA cable connected to the correct spot and the controller for that connection turned on in the bios.