This provides maximum bandwidth to the two MPX Module bays, ideal for graphics performance. PCIe slots 1 and 3, the primary MPX Module slots, each connect directly to an x16 root port on the Xeon processor. All PCI Express slots and Thunderbolt controllers connect either directly or through this PCIe fabric.

Mac Pro PCI Express expansion capabilities are enabled by four x16 root ports on the Intel Xeon W processor, providing 64 PCI Express lanes and a high- performance PCI Express switch fabric. High-Performance PCI Express Switch Fabric So I suggest that what is provided is almost full coverage of all slots at top possible speeds, but just like in the Mac Pro 2019 model, falls ever-so-slightly short of that ideal. To provide Fewer lanes, even though they are at PCIe 4 speeds, opens Apple up to ridicule that their Apple-Silicon solution is not completive with Intel. I have come across some information that is not definitive, but is tangentially-related to your query in an Apple article about the Intel Mac Pro 2019 model.Įight PCI Express slots are enabled by the 64 PCI Express lanes provided by the Intel Xeon processor and a high-performance PCI Express switch fabric on the main logic board that includes a 96-lane PCI Express switch.

Apple expansion slot utility download