What socket 771 motherboard is curently in every MacPro out there?

an apple specific one that is next to impossible to getan apple specific one that is next to impossible to get

I believe it's based on the Intel 5000X chipset.

it might be the SUPERMICRO MBD-X7DA3+

Nope, you will notice that the board you listed doesnt use Riser cards for the RAM.
Also there is an issue where the MacPro board is mounted "upside down" on the opposite side for a "normal" motherboard.

The Northbridge is Intel 5400B Rev C0
The Southbridge is Intel 6321ESB Rev 09

The name for the Mac Motherboard is Mac-F42C88C8
Here is a whole bunch of info grabbed from CPU-Z

There's actually at least two different logic boards.

The original Quad core Mac Pro 1.1 has one based on the Intel 5000X chipset. It is Mac- specific.
It appears to have been manufactured by Foxconn, a major motherboard maker who also makes them for HP, Intel and others. They also make a lot of the Laptops out there.

The 2008 model 8 core Mac Pro 3.1 logic board is based on the Intel 5400 chipset and supports faster RAM and PCIe 2.0, but is otherwise similar.

Was there a 2.1?
Anybody?

Keri