ATX12V v2.4
The ATX12V 2.4 specifications were published in April 2013. It is specified in Revision 1.31 of the 'Design Guide for Desktop Platform Form Factors', which names this as ATX12V version 2.4.
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ATX12V v2.51
The specifications for ATXV12 2.51 were released in September 2017 and introduced support for
Alternative Sleep Mode (ASM) which supersedes the traditional
S3 power state. Windows 10 implements this functionality as
Modern Standby.
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ATX12V v2.52
The specifications for ATXV12 2.52 were released in June 2018 introduces minor changes to the standard, most notably it requires power supply manufacturers to ensure power supplies with
Alternative Sleep Mode (ASM) support are able to withstand power cycles every 180 seconds (480 times per day or 175,200 per year). Power supply fans are also recommended to turn on with at least a two second delay for an improved user experience.
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ATX12V v2.53
The specifications for ATXV12 2.53 were released in June 2020 and constitute another minor update to the ATX standard. ATXV12 2.53 makes further recommendations on efficiency and references the
Energy Star Computers Specification Version 8.0 which was finalized in April 2020.
Quelle:
https://en.wikipedia.org/wiki/ATX#ATX12V_2.x