Z790 vs Z890: What's the difference?

On the CPU side, the new Intel Core Ultra 200 CPUs (Arrow Lake-S) come with 20 PCIe 5.0 lanes split x16 for GPU (or x8-x4-x4) and 4 lanes for M.2 PCIe. It also includes 4 lanes of PCIe 4.0 for an extra port (PCIe or M2.PCIe).

This extra 4 PCIe Gen 5.0 lane compared to previous Intel Core 14th generation on the CPU will free the chipset to deal with 1 or 2 M2 PCIe slots, so the Z890 chipset will have 24 lanes Gen 4.0 and no PCIe 3.0, whereas the Z790 had 20 lanes Gen 4.0 and 8 PCIe Lanes.

However, if we add up all the lanes from the CPU and chipset, we're left with a total of 48 lanes in both cases.

So the main change is to the PCIe generation and the repartitioning of the CPU and chipset, however, the DMI connection between CPU and chipset remains the same with 8 lanes PCIe 4.0. additionally, the Z890 chipset only supports DDR5, unlike the Z790.

The Thunderbolt 4.0 is now built directly into the CPU, but unfortunately there is no native support for USB4.0.

You'll probably find it on the high-end motherboard via an external chip, as was already the case on the Asus X670E Creator, but this will cost some of the PCIe lane that can't be used for anything else.