Hardware Reference
In-Depth Information
Table 4.52. CD Audio Connector
Table 4.53. Telephony Connector
Table 4.54. ATAPI-Style Line In Connector
Note
Some boards have a board-mounted piezo speaker. It is enabled by placing a jumper over pins
3 and 4, routing the speaker output to the board-mounted speaker. Removing the jumper enables
a conventional speaker to be plugged in.
Most modern motherboards have three or four fan connectors for use with the processor fan, rear
chassis fan, front chassis fan, and voltage regulator (power) fan (see
Table 4.55
)
. They generally use
the same 3-pin connector, with the third pin providing a tachometer signal for optional speed
monitoring. If the motherboard is capable of monitoring the fan speed, it can sound an alarm when the
fans begin to slow down due to bearing failure or wear. The alarm sound can vary, but it normally
comes from the internal speaker and might be an ambulance siren-type sound.
Table 4.55. Fan Power Connectors
Caution
Do not place a jumper on this connector; serious board damage will result if the 12V is shorted
to ground.
System Bus Types, Functions, and Features
The heart of any motherboard is the various buses that carry signals between the components. A
bus
is a common pathway across which data can travel within a computer. This pathway is used for
