intel SE7210TP1-E - eps power supply problem - won't boot

Please help.

I have a intel SE7210TP1-E server board. It has worked fine (and still
does) with a Enlight 600W EPS power supply (EN-860B3E1). However, I
need this board to work with a different power supply. I bought an ams
mercury eps power supply (PP-4603EPS). Once plugged in and power
button hit all that would happen is the cpu fan would spin for a second
then nothing. Fearing this was due to a bad power supply, I sent it
back and got an antec EPS True 550 power supply. Same result.

I have removed the ram. same result. removed the cmos battery -
overnight. same result.

Each and every step I tried the orginal Enlight power supply with
success.

The reason I can't continue to use the enlight supply. Is that it does
not fit in the case that is now dedicated for this board.
Pulling my hair out.

And help would be appreciated.

Thanks
Dave