Mac Pros - Dual Port Fibre Card - which slots?

A pre-xSan question...

Running into some conflicting info on which PCI-Express slots to install these cards in.

I have a MacPro (early 2009) that has a Kona 3 in slot 2 (the x16 slot)

I have some other workstations that are MacPro (mid-2010) that have have slot 2 open.

The fibre card instructions say:
-PCI Express with eight lanes (up to 2.0 GB/s, full duplex)

The product description says:
-This card runs at full bandwidth in a four-lane or eight-lane PCI Express slot

The MacPro "Servers" that will become the MDCs had the cards installed at the factory in Slot 4 (an x4 slot).

So I'm not sure where to put them! I'm sure I can just stick the cards in the x16 slots on the 2010s and not lose out. The big question is on the 2009 with the Kona card. Do I need to move the Kona to slot 3? It'd be nice to leave it where it is and put the FC card in slot 4.

Any advice would be great.

Thanks,
Chris

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.

any earlier machine (Model Identifier 1,1) used the Expansion Slot Utility. The later machines had slots 1 and 2 as x16 lane, and slots 3 and 4 as x4 lanes. On a server, if you need two x16 lane cards, you can move the graphics card into slots 3 or 4 - I do this all the time. The Apple LSI Logic FC card is a x4 lane card, and the AJA Kona series can run in x4 or x16 lane slots.

You will find that as you use more modern cards, that require x8 lanes (think modern ATTO cards), you will see a huge performance difference between the x4 and x16 lane slots.

Bob Zelin