ATX Power supply "Standard"????

[DKD]

I have recently ran into an issue with the new ATX power supplies. Specifically, I purchased 5 Xion-630W ATX power supplies from a national vendor for ready spares for our corporate repair facility.

The issue is which ATX standard version is needed? A good majority of our production machines require the ATX v2.1 while a few of our very newest machines can utilize the new ATX v2.2.

The issue at hand is that pin 18 on the 20pin ATX mainboard connector is supposed to be a -5vdc output and yes the older boards do require it.

With the new power supplies (v2.2) that we received, you can seperate the last 4 pins effectively making the connection to a 20pin maindoard BUT, under the new standard, pin 18 is disconnected and therefore dead rendering the power supply useless. I think you can appreciate the confusion this caused until I found the culprit.

What I do not understand is that when the standard changed, why wasn't the name or something changed as well so that the rest of us could differentiate between the two as was done in years past such as the XT standard vs. the AT standard vs. the ATX standard?

 

[delluser1]

-5v became optional on power supplies in 2003 with the birth of the ATX 1.3 spec, so it's not really a new specification.
If your 2.2 spec psu isn't working on a machine that had a 2.1 psu it could be due to not enough of a 12v load at start up. Try adding a fan or 2 to the system and then see if your 2.2 psu works.

 

[JohnnyLucky]

XT?? early 1980's?? That's ancient history!