Drive bays – They are slots, usually in the front, for disk drives mainly for removable media drives such as optical, floppy disk, and Zip drives. These have openings in the front and usually come with plastic covers in case they are not used. They are present in two sizes i.e. 51⁄4-inch and 31⁄2-inch for optical and floppy disk drives.
Speakers – It is present to provide basic sounds to the user for playing warning beeps and is small.
Key lock –Older computers had key locks, few newer ones do to prevent computer booting. Floppy drive locks were used earlier for preventing data access.
Buttons – Buttons for power and reset are present to turn on or off a computer and the Reset button, simply turns power off and on the computer.
I/O Shields – They are metal plates surrounding ports of motherboard at back of the chassis. They snap in place to shield from electronic interference and provide openings in the chassis for ports.
Power supply – They are usually supplied with the chassis in the market. The power rating of the power supply (also called as SMPS) is dependent on the form factor of the chassis.
Bezel –The front plastic faceplate of chassis on which drive bays, LED and buttons are mounted
LED and Miscellaneous Cables – LED indicate power and hard disk activity status. LED are present in the front of the chassis. Miscellaneous cables connect LED to the motherboard.