I'm fairly certain this PSU was for a P4 board and the +12.8 VDC rail was on the 20+4 or 20+6 connector as the Vcpu pins. Looking at some of the older manuals on Manual Libs, shows that this is likely correct:
These were very OEM power supplies which fell "in and around" the ATX12V v1.2/1.3 specs.
