Hardware Reference
In-Depth Information
number of both proprietary and industry standard designs.
See the
Chapter 4
section, “
Motherboard Form Factors
,”
p.
155
.
Modern Form Factors
The power supply form factors detailed in the following sections are the standards used in current
systems. ATX is far and away the most common of these, but if you work on a variety of PC types,
you are likely to encounter the other types listed here.
ATX/ATX12V
In 1995, Intel saw that the existing power supply designs were literally running out of power. The
problem was that the existing standards used two connectors with a total of only 12 pins providing
power to the motherboard. In addition, the connectors used were difficult to properly key, and
plugging them in improperly resulted in short-circuiting and damage to both the motherboard and the
power supply. To solve these problems, in 1995 Intel took the existing popular LPX (PS/2) design
and simply changed the internal circuitry and connectors (while leaving the mechanical shape the
same), giving birth to the ATX power supply form factor (see
Figure 18.1
)
.
