To do this on my Acer: (firstly, laptop has to be powered off).

Disabling UEFI and switching it to Legacy (which also disables secure boot) will allow me to tell the computer to look at other locations when booting up.

it doesn't care if I have a windows repair CD, or USB recovery flash drive plugged in. With UEFI (and secure boot) enabled, my computer is ONLY looking for the operating system on the internal HDD (or SSD).

my Acer has the “no bootable device” error when booting up.

if you hear clicking, then your HDD is more than likely toast. and these make a noticeable sound when they are running (smooth high pitched whirling). More often than not, these are standard with many factory systems. Almost like a high-tech record player there's a spinning platter that stores the data (the vinyl), and a read/write arm with a magnetic head that access the platter (not unlike the tonearm and cartridge-needle on a record player).

these are traditional hard drives with mechanical moving parts. they are fast! they tend to be included with higher end systems or as aftermarket upgrades. Think of it like how a usb flash drive works. Even if they fail, there will never be any clicking sounds, vibrations. there are no mechanical movements in these hard drives. here are some important points that need clarifying.

Some misleading and incomplete info in a few of these replies.

No boot disk windows 8