Hi, welcome on board. We were all new once and started at post #1.... I'm not far behind you.
It's gonna work out expensive keep buying new drives, can we be sure it is the drive, is it possible to try one of the faulty drives in another machine or a external caddy, we need to be sure it is the drive and not the computer.... we don't know if something has happened to the mobo, drive controller for example...... are all these the same brand, are they from a reputable source, what about a warranty on them any chance of a return? So many questions comes to mind but we do need to be sure it's the drive first of all.
If using in a caddy, ie a slave as opposed to a master bootable drive you will have to alter the jumper setting from Master to slave, doing this will allow you to see the files on it proving the drive is mechanically OK but the fault 'may' lie with the boot sector that's used for booting.
Edited by Pentodes, 03 October 2015 - 02:48 PM.