July 2003
Beginner to intermediate
874 pages
38h 13m
English
Content preview from PC Hardware in a Nutshell, 3rd Edition
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ATX Main Power Connector
Table 26-12 lists the pinouts for the ATX Main Power Connector of an ATX or ATX12V power supply. This is a 2X10 connector with Pin 1 keyed. The motherboard connector is a Molex 39-29-9202 or equivalent. The power supply connector is a Molex 39-01-2200 or equivalent. All wires are 18 AWG, except Pin 11, which is specified as 22 AWG. For power supplies 300W or larger, the specification recommends using 16 AWG wires for +3.3VDC, +5VDC, and COM (ground). Note that wire colors are those recommended and commonly used, but may vary.
Table 26-12. ATX Main Power Connector configuration
|
Pin |
Color |
Signal |
Pin |
Color |
Signal | |
|---|---|---|---|---|---|---|
|
1 |
orange |
+3.3VDC |
11 |
orange |
3.3VDC | |
|
2 |
orange |
+3.3VDC |
12 |
blue |
-12VDC | |
|
3 |
black |
COM |
13 |
black |
COM | |
|
4 |
red |
+5VDC |
14 |
green |
PS-- ON | |
|
5 |
black |
COM |
15 |
black |
COM | |
|
6 |
red |
+5VDC |
16 |
black |
COM | |
|
7 |
black |
COM |
17 |
black |
COM | |
|
8 |
gray |
PW-- OK |
18 |
white |
-5VDC | |
|
9 |
purple |
5VSB |
19 |
red |
5VDC | |
|
10 |
yellow |
+12VDC |
20 |
red |
5VDC |
In addition to supplying various standard voltages, this connector includes four special-purpose pins:
- Pin 8 (PW_OK)
PW_OK is the ATX equivalent of the AT Power Good signal, which the power supply asserts once it has stabilized. The motherboard will not attempt to boot until the power supply asserts PW_OK.
- Pin 9 (5Vsb)
5Vsb is the +5V standby circuit, which supplies +5V at low amperage to the motherboard even when the power supply is off. Any ATX power supply must provide at least 10 mA 5VSB, but motherboards ...
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