ATX Version Questions

[vxspiritxv]

Anyone know a site with a quick rundown of the different versions?
1.3
2.03
2.1
2.2

Now if only hardware makers wrote a changelog like opensource software makers

 

[FreiDOg]

1.0 Feb, 2000 • Public release
1.1 Aug, 2000 • Increase 3.3 V current; add more explanation for power sharing; do
minor edits and format fixes
1.2 Jan, 2002 • Typical Power Distribution. Change +5V loading on all power
supplies distribution tables defined in DG to 0.3A
• PS_ON# Add text “The power supply should not latch into a
shutdown state when PS_ON# is driven active by pulses between
10ms to 100ms during the decay of the power rails.”
• Remove –5V from all power distribution tables.
1.3 April, 2003 • Update Power and Current guidance
• Added efficiency guidance at typical and light load
• Increased min efficiency at full load from 68% to 70%
• Serial ATA* connector definition added
• Acoustic levels added for low noise power supply design
• Reformat and update revision table
• Update Disclaimers
• Remove guidelines for ATX
• Remove guidance for –5V rail
• Updated guidance for Energy Star and stand by efficiency
2.0 February, 2003 • Added Terminology section
• Updated power and current guidance
• Includes 250W, 300W, 350W, and 400W guidance
• Updated cross regulation graphs
• Updated load tables
• Updated required efficiency targets. Added recommended
efficiency targets.
• Increased required minimum efficiency at typical and light load.
• Main Power Connector changes to 2x12.
• Aux power connector removed.
• Required Serial ATA Connector.
• Isolated current limit on 2x2 connector for 12V2 rail.
2.01 June, 2004 • Updated 3.3 V remote sense pin # on the main power connector
• Updated 12V2 DC Output Noise/Ripple information
• Removed -5V reference
• Updated 5Vsb maximum current step

Copied sraight out of the ATX PSU design guide (pdf).
2.1 and 2.2 are part of the ATX spec but don't all affect the PSU

 

[Laforge]

Anyone know a site with a quick rundown of the different versions?
1.3
2.03
2.1
2.2

Now if only hardware makers wrote a changelog like opensource software makers

It's not a 5 item list.

Google is your friend


Freidog's list doesn't cover everything ..

Such as *size* constraints, etc..

 

[Ice Czar]

the ATX vs ATX12V spec does present some confusion since at one point the mobo and the PSU spec where both ATX
ATX12V is a subset of the overall ATX spec

ATX12V v1.3
basic old spec with a 4 pin auxillary +12V power connector and more amp devoted to the +12V rail and greater efficiency than the previous spec

ATX12V v2.0
increases efficiency again
splits the +12V rail into +12V1 & +12V2
increases the amount of amps per wattage class devoted to the +12V rails
adopts the EPS12V 24 pin main power connector

ATX12V v2.01
drops guidelines for the -5V rail
again increases the amount of amps per wattage class devoted to the +12V rails

ATX12V v2.XX
will likely adopt the 8 pin auxillary +12V mobo connector from the EPS12V spec
possibly will split the +12V into 3 rails per the EPS12V "common plane" spec
and increase the amount of amps per wattage class devoted to the +12V rails yet again
all to address the recent change in the PCI-E spec (it doubled on max power from 75W to 150W all +12V) and to consolidate the two competing specs
Server System Infrastructure (SSI) & formfactors.org, both driven by Intel


VVVVVVV somewhat old history now
(since ATX12V v2.0 & v2.01 is now widely implemented)

Power supplies become increasingly expensive

When I initially asked about this on a mailing list, Solaris x86 advocate Al Hopper told me I was drowning in my tea, and that it was "all very simple". I love the simplicity of Unix people.

He explained that the later P4 CPUs take their power from a 12 Volt feed and, using the onboard voltage regulators, generate the high current, low-voltages they need to operate (anywhere from ~ 1.6V to around 2.7V). So the first requirement is a PSU that has plenty of power available from the 12V supply. Since the older ATX compatible PSUs didn't supply much current from the 12V section you have to ensure that your new PS delivers enough current (or power in Watts) from the 12V section. That's why using your old P3 ATX PS is a big "no-no".

He then described the history of the post-P3 power supply mess:

The earlier Athlon motherboard manufacturers decided to solve the 12v problem by using an additional 4-pin square connector to get the extra 12V those CPUs required. However many older PSUs didn't provide the 12V 4-pin square connector.

The motherboard makers then wised up and decided that there was nothing magical about a square 4-pin connector, so they put a normal hard disk type socket on the motherboard and provided the 12v power via a standard hard disk (4-pin inline) connector. Problem solved - you may now use your older PSUs provided they supply sufficient 12V current (many did not).

Further confusion came from PSU manufacturers not specifying the capabilities of the PSU in a way that allowed the end user to verify it's 12V power output rating.

In the meantime the ATX spec was saying "use the new 6-pin" inline connector - and very few motherboard makers implemented it.

Just to be sure, some motherboard makers, implemented *both* the hard disk style 4-pin inline connector and the square 4-pin connector. They said "use either or both in any combination you like".

The spec then evolved to the 24-pin main connector. Again, most motherboard manufacturers did not wish to make their customers mad by mandating that they replace their power supplies. This might cause their customers to avoid motherboard upgrades. Some used a "special" 24-pin connector with the extra 4-pin connection blocked off, or colored so that the user could plugin a 20-pin plug into the correct end of the 24-pin socket on the motherboard. Many others simply ignored the 24-pin requirement in the specs. Again - problem solved - use your older PSU.

Changes to the spec recently have been driven by PCI-E
and the boards are rapidly approaching the power levels of older dually mobos
thus why Ive taken the rumors the EPS12V & ATX12V specs merging very seriously
dual CPU \ PCI-E mobos are getting seriously power hungry (workstation class)
as evidenced by the new 850Watt ETX PCP&C with 60 amps on the +12V rails (4 split plane)
(2 CPU + 2 SLi + storage)