Au-31 mother baoards E machine

We have had 6+ E machines with the Au-31 mother boards go down, just won't boot. Not the Disk drives, not the processor and not the power supply.
They were all turned off the way we are supposed to. All other E machines not with the Au-31 no problem. I am using the power supply and the disk drives in a case I had with a new mother board and had to reload system info. on a spare drive to get going again, really need to get the old machine runining. Any Ideas, ps. did try tech support and they gave me 3 pages of try this and that no luck.
Tony