https://www.techpowerup.com/243419/a...ter-pcie-lanes

AMD is reportedly readying a new high-end motherboard chipset positioned higher than even its upcoming X470 chipset, which makes its market debut on April 19. The new Z490 chipset, as it's called, is emerging to be significantly different from X470, and could finally overcome its biggest limitation - downstream PCIe connectivity. While the X470, like its predecessor, puts out just 8 downstream PCIe lanes, which are PCI-Express gen 2.0 at that, the new Z490 will put out a total of 12 PCI-Express gen 3.0 downstream lanes, which will power additional bandwidth-hungry devices, such as additional M.2 slots, external USB 3.1 controllers, 10 GbE controllers, etc. The Z490 was first leaked through a GIGABYTE Aorus internal presentation.

In its current implementation, socket AM4 motherboards have a total of 24 PCI-Express gen 3.0 lanes from the AM4 SoC, besides 6-8 gen 2.0 lanes from the chipset. From this SoC budget, 16 lanes are allocated for PEG (PCI-Express Graphics), 4 lanes as chipset-bus (connecting the SoC with the chipset), and the remaining 4 lanes powering one 32 Gbps M.2 slot. Additional M.2 slots are either gen 2.0, from the chipset's downstream lane budget, or split from the PEG budget. The Z490 overcomes this with a downstream PCIe root complex that's not just 50% broader, but also twice as fast, with PCI-Express gen 3.0. The rest of its feature-set appears to be identical to the X470. There's no timeline on when we can expect Z490 to launch.