Hardware Reference
In-Depth Information
•
Single main keyed internal power supply connector
—The ATX specification in-
cludes a keyed and shrouded main power connector that is easy to plug in and install.
This connector also features pins for supplying 3.3V to the motherboard, helping to
minimize the use of built-in voltage regulators that are susceptible to failure.
See
“
Motherboard Power Connectors
,”
p.
857
(
Chapter 18
, “
Power Supplies
”
).
•
Relocated CPU and memory
—The CPU and memory modules are relocated so
they can't interfere with bus expansion cards and can easily be accessed for upgrade
without removing any of the installed bus adapters.
•
Relocated internal I/O connectors
—The internal I/O connectors for the floppy and
hard disk drives are relocated to be near the drive bays and out from under the expan-
sion board slot and drive bay areas.
•
Improved cooling
—The CPU and main memory are designed and positioned to im-
prove overall system cooling compared to Baby-AT and older designs.
•
Lower cost to manufacture
—The ATX specification eliminates the need forthe rat's
nest of cables to external I/O port connectors found on Baby-AT motherboards.
Figure 4.13
shows the typical ATX system layout and chassis features, as you would see
them looking in with the lid off on a desktop, or sideways in a tower with the side panel
removed. Notice how virtually the entire motherboard is clear of the drive bays and how
thedevices suchasCPU,memory,andinternal driveconnectors areeasytoaccess anddo
not interfere with the bus slots.
Figure 4.13
Typical ATX system layout.
