System Cases

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System Cases ( also called Cabinets)

The size of the system case is often determined by the motherboard form factor. The most common motherboard form factors that determine case size are AT and ATX.
• AT
o Measures 12" x 13.8"
o Not compatible with ATX cases
o CPU sits in front of expansion slots
o Power cable runs from the system case power switch to the power supply
• ATX
o Measures 12" x 9.6"
o CPU and memory slots sit alongside expansion slots
o Power cable runs from the system case power switch to the system board
System cases come in three basic sizes:
• Desktop cases are usually used for low-end systems that are not meant to be upgraded.
o Desktop
o Slimline
• Tower cases can be as high as two feet tall. They have extensive room for expansion.
o Minitower (does not provide room for expansion)
o Midsize (six expansion slots and four drive bays)
o Full-size (used for high end PCs and servers)
• Notebook cases are generally proprietary and often vary among models.

Items included with a system case:

Item	Description
Power supply	An appropriate power supply for the type of system board the case supports.
Power cable	A cable from the power supply to the AC wall outlet.
Indicator light cables	Cables from the indicator lights on the front of the system case. These cables attach to the system board.
Power switch cable	A cable from the power switch on the front of the system case to the power supply (for an AT system case) or to the system board (for an ATX system case).
Reset cable	A cable from the reset switch on the front of the system case to the system board. The reset button restarts the computer without completely disengaging the power supply (often called a "soft boot").
Speaker	System cases come with a simple internal speaker. This speaker communicates audio errors during the POST.
Speaker cable	A cable from the internal speaker to the system board.
Rubber or plastic feet	Attachments placed on the bottom of the system case to prevent the case from scratching the surface where it is placed.
System board mounting standoffs and screws	Items to attach the system board to the mounting plate in the system case.