PCIe Bifurcation?

[TCM]

Hi,

I hope my question is placed here best.

What exactly is PCIe bifurcation? I'm using a Supermicro X9DR3-F with a single E5-2609. What do I gain/lose from changing these BIOS settings? Shouldn't these be GEN3 instead of GEN2 in the first place? How do I know which ports belong to which physical port/device?

Edit: Another thing: according to the block diagram, the PCH is connected to the 2nd CPU? How can this work if the socket is empty?

Edit2: When I change IOU1 - PCIe Port from x4x4 to x8 the SCU disappears and the NICs change in ESXi from vmnic[01] to vmnic[23].

Thanks

 

[shawkie]

I concluded that the CPU sockets are labelled the wrong way around in the diagram. Also the ports on the diagram are called 1A, 1B, 2, 3A and 3B whereas in the BIOS I think they are called 1A, 1B, 2A, 3A and 3C. I have no idea why they aren't set to GEN3 by default (especially 1A which apparently goes to the PCH and is labelled as G3 in the diagram). I'm also unable to get my GTX 670 cards to run in GEN3 mode on this board and in some cases enabling GEN3 in the BIOS causes a boot failure (no video).