Drive bay

Over the years since the introduction of the IBM PC, it and its compatibles have had many form factors of drive bays.

This is the size of the internal (screwed) part of the bay, as the front side is actually 5+7⁄8 inches (149.2 mm).

Hard drives in modern computers are typically mounted in fully internal 4″ (nominally 3.5″) bays.

Most modern computers do not come with a floppy drive at all, and may lack any externally accessible 3.5″ bays.

Drive bays are most commonly used to store disk drives, although they can also be used for front-end USB ports, I/O bays, card readers, fans, fan controllers, RAID controllers, tool storage, and other uses.

Some computers have a small system monitor LCD mounted in a drive bay.

Then, any necessary power, data transfer, and other cables are routed into and connected to the rear of the drive.

Since computers have 12 V rails on their motherboards, some computer hobbyist websites even sell addons for cigarette lighter receptacles to power or recharge devices made to draw power from automobiles, though USB is already available for charging devices like cell phones and portable media players.

Drive bay-compatible computer case accessories that do not connect to the motherboard or power supply at all are also common, such as small storage drawers or even cup holders.