When your computer is started, it undergoes a Power-on self-test (POST) at which point the BIOS (Basic Input/Output System) identifies the attached peripherals. If your hard disk drive is not detected, you may have a physical problem with the drive controller board. If the drive shows a different identification string, it is clear that there is an issue with the hard drive controller board.
Hard Drive Not Appearing in BIOS
If this still occurs after checking for the obvious potential problems, such a cable becoming detached, the problem is almost certainly of a serious nature. Swapping cables, and checking different connectors on the motherboard, or mass storage card, is unlikely to solve the problem, as failures of those components are rare, but not unheard of. It is important to take anti-static precautions if you open the case of your computer, as failure to do so, could potentially cause additional component failures. Continual attempts to reboot your computer may also have the potential to cause further damage, making data recovery a more complex process.
Hard Drive Appears as Different Device in BIOS
Some models of drives, such as many Western Digital hard disks, will show a different identifier string in the BIOS under some circumstances such as when a controller board failure has occurred. This could show up as string similar to “WDC ROM MODEL-HAWK” in which case you require data recovery in order to access your files. In most cases, this failure does not cause any damage to the data held on the disk, as long as another failure has not also occurred. If you see an identification string similar to this, it is important to power the machine down, as repeated attempts to reboot the computer could compound the problem.
Hard Drive Controller Board Issues
The hard drive controller board is required to serve many functions. It has to supply the correct power to the disk motor, which is used to spin the platters at the designated speed. It is also the input/output interface between the hard disk drive and the host computer, and must also control the read/write heads, to correctly service requests to read or write data from or to the disk platters. It is easy to understand, that even the smallest failure on the controller board can lead to erratic behaviour of the hard disk drive.
The most common causes of failure to the hard disk controller board, are excessive heat, power surges, damage to the firmware, malfunction of a component or through physical damage. All of these failures will render the data stored on the hard disk drive completely inaccessible. As already stated, it is important not to make further attempts at powering the drive in the computer, and to seek a professional data recovery solution.