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PC Hardware in a Nutshell, 3rd Edition
book

PC Hardware in a Nutshell, 3rd Edition

by Robert Bruce Thompson, Barbara Fritchman Thompson
July 2003
Beginner to intermediate content levelBeginner to intermediate
874 pages
38h 13m
English
O'Reilly Media, Inc.
Content preview from PC Hardware in a Nutshell, 3rd Edition

ATX12V Power Supply Connector

With the introduction of the Pentium 4 processor, Intel extended the ATX 2.03 specification to define a new type of power supply called ATX12V, which is a superset of ATX 2.03, and is now incorporated in the ATX Specification 2.1 and the ATX/ATX12V Power Supply Design Guide Version 1.2. ATX12V power supplies include an additional 2X2 4-pin +12V power connector, shown in Table 26-15. The motherboard connector is a Molex 39-29-9042 or equivalent. The power supply connector is a Molex 39-01-2040 or equivalent. All wires are 20 AWG. Wire colors are standard. The purpose of this new connector is to deliver more +12V current to the motherboard than is available from the standard ATX main power connector. The presence of the 4-pin +12V connector indicates that a power supply is ATX12V. The absence of that connector indicates that it is a standard ATX power supply.

Table 26-15. ATX12V Power Supply Connector

Pin

Color

Signal

Pin

Color

Signal

1

black

COM

3

yellow

+12VDC

2

black

COM

4

yellow

+12VDC

According to Intel’s policy, all Pentium 4 motherboards and all power supplies used with those motherboards must include the 4-pin +12V connector. Because installing such motherboards in existing systems may also require upgrading the power supply, some third-party motherboard makers have produced motherboards that lack the 4-pin +12V connector. This allows those motherboards to be installed in existing systems without a power supply upgrade, but ...

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Publisher Resources

ISBN: 059600513XErrata Page