C410x revision needed for 8:1 mode

I recently acquired a C410x PCI Express Expansion chassis to allow multiple PCI-e GPUs to be connected to a single PCI-e slot.

The chassis that I have has a sticker indicating that it supports 8:1 mode, i.e. connecting 8 GPUs to a single slot. However, it actually only supports 4. I saw from the manual and a Dell blog that the oldest versions only supported 4, while the newer versions support 8.

I was wondering if anybody knows what revision is required to support 8, specifically what revision of the middle board? I am considering buying a new middle board to get the support for 8. My chassis is Rev A00, but I have seen reports of other chassis A00 versions working with 8. I know that at least board revisions A00 and A01 exist, but I am not certain if even higher revisions also exist and are necessary for 8:1.

Finally, is middle board replacement alone likely to be sufficient for this or would I need new iPass boards too?

Thanks for any help.

Tom