The computer may not "see" the hard drive due to problems in the BIOS, a broken power cable connection, incorrectly set priority of BIOS boot properties, and others. The machine will not find the hard drive if the power supply fails.
The computer may not "see" the disk for many reasons, some of which cannot be dealt with on its own, you will need the help of a competent specialist. However, if you know the reasons for such a problem, then you can save yourself from rash actions.
The main reasons for this problem
Most often, the hard drive is not recognized in the BIOS, that is, it is impossible to boot anything from it. You can confirm your assumptions if you boot from another device, for example, from another hard drive or CD, by going to Computer Management, selecting Device Manager and looking for the required drive. If the machine "does not see" it, then the problem is in the BIOS. In turn, the hard drive in the BIOS may not be detected due to a broken connection between the power cable and the interface cable. The fact is that several cables leave the power supply at once: some are connected to the motherboard, others to hard drives. If the HDD power cable is connected incorrectly, the activity indicator on the system unit will be constantly on.
The same problem can arise if the jumpers are incorrectly positioned to switch the screw to the desired operating mode. It also happens that there are no jumpers at all. Less common is the situation when the SATA hard drive is not detected. This is where a BIOS reset can help. If the PC "does not see" the IDE hard drive, then you can check the inclusion of this controller in the BIOS.
Reasons why the drive is not recognized in Windows
Most often, the system does not see the hard disk if the priority of the boot properties is incorrectly set in the BIOS. For example, in the characteristics responsible for loading the operating system, the first number is CD-ROM, and the second is the hard disk. In this case, if the drive contains not a bootable disk, but some other, the system will not be able to recognize the hard disk. An external hard drive may not be detected due to overcurrent in the USB ports of the computer. This situation is typical when a large number of peripheral devices are connected to USB ports, which are used both for exchanging information and receiving power.
The machine may not find the hard disk due to a defective power supply. If it makes loud, uncharacteristic sounds when rebooting, then most likely it lacks the power of the power supply. The reason why the computer does not detect the second hard drive may be incorrect cable connection or a conflict between two hard drives of the same brand.
