Re: Mac Pros - Dual Port Fibre Card - which slots?

Running it yields this:
"Expansion Slot Utility is not intended to run on this system."

So I experimented. I put a card in the x16 slot on one machine and in the x4 slot on another. I've got 2 blue lights on the back of each card and the manual tells me that means everything is running at 4 Gbit/s. So based on that it seems that an x4 slot is okay.