Thanks for the answers. I have plugged the 12V into the CPU power connector, per the manual. There is no other plug nearby (or on the board for that matter).
Does the Mobo circuits or BIOS check for something besides the presences of cpu, cpu fan, and PSU good prior to starting up? Based on the troubleshooting steps suggested, it appears that is all that is required to switch on the voltage rail connections within the mobo.
As to the quality of the units, I checked the PSU pins and they all had valid voltages. Perhaps they can't source enough current but that is a unlikely failure mode.
My next cumbersome step is to validate the PSU in my other computer and then try the other computer PSU for the mobo.