ok - so thats a PE1 single lane board

since it works fine in a 3,1 MacPro - it is possible that it requires a firmware update to work in newer 4,1 or 5,1 MacPro

I'll check with AS to confirm that this is the issue
(This is usually only required for PE1 single lane cards - not PE4)
Please email me separately for the FW upgrade and further details.

S