The PCI Special Interest Group (PCI-SIG) has published proposals for PCI Express 0.3 version 7.0 specifications. The company will continue to update this data, but for now they tell us that a single PCIe 7.0 lane will transfer twice as much data as PCIe 6.0. The latest version, by the way, is twice as fast as PCIe 5.0 and so on. PCI Express 7.0 will appear in 2025, but not everyone has switched to PCIe 4.0 yet.
Current draft specifications will be forwarded to all PCI-SIG participants for further development. One PCIe 16 x7.0 slot will provide up to 512GB/s throughput, by the way.
