https://wccftech.com/asus-b660-motherboard-leak-suggests-mainstream-platform-limited-to-pcie-gen-4-no-pcie-gen-5-support/

ASUS B660 motherboards were leaked by Noctua a few days ago but Videocardz has managed to obtain packaging information which suggests that they might lack a significant feature of the Intel Alder Lake CPU lineup.

A packaging picture of the ASUS PRIME B660-PLUS D4 motherboard has leaked out which will be coming to the retail segment soon. The motherboard is expected to retain most of the specs of its Z690 sibling though it has one big change. The motherboard is listed as a PCIe Gen 4 only variant.