Thanks TP, The GTX cards work fine on another motherboard. I have tried the three GTX cards individually, with the same result. I don't understand why it fails on new Nvidia GTX gpu's but works fine on old GPU. If all else fails I can do a gpu swap with a workstation in the office that has two Quadro 2000's.
Haven't posted on GPU forum, but that's a good idea.
Still hoping Supermicro support will provide clues.