Intel ATX 0.9 - Manual (Page 6)

Intel ATX Power Supply Design Guide
Version 0.9
Page 6
1. Scope
This document outlines a reference ATX power supply that complies with the ATX
Specification, Version 2.02 for motherboards and chassis. It is intended to provide
additional power supply design information not detailed in the ATX 2.02 specification,
including information about the physical form factor of the power supply, cooling
requirements, connector configuration, and pertinent electrical and signal timing
specifications.
This document is provided as a convenience only and is not intended to replace or
supplement the user’s independent design and validation activity. It should not be inferred
that all ATX power supplies must conform exactly to the content of this document. Neither
are the design specifics described herein intended to support all possible system
configurations, as system power supply needs will vary widely depending on application
(desktop / workstation / server), intended ambient environment (temperature, line voltage),
motherboard power requirements, etc.
With a few modifications, a standard PS/2 † power supply can support an ATX form-factor
system. At a high level, these modifications include consolidating various motherboard
connectors into a single 20-pin connector, adding +3.3VDC and +5VSB output supply
rails, adding a PS_ON# control input, and possibly repositioning the fan and/or venting
locations.