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.
ASUS B660 Motherboards Seemingly Lack PCIe Gen 5 Support, Only Limited To PCIe Gen 4 With Alder Lake CPUs
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.
The PRIME Z690-PLUS comes in both DDR5 and DDR4 flavors so that's nothing new but it looks like we might be seeing only DDR4 support on B660 motherboards. But the main thing to note is PCI-e support. The ASUS B660 motherboard is listed as a PCIe Gen 4 model whereas all Z690 boards are PCIe Gen 5 compliant. It may be possible that all B660 motherboards might be limited to PCIe Gen 4 support only while the higher-end Z690 boards offer Gen 5 support.
But in the end, it's not B660 or Z690 PCH that's providing the PCIe Gen 5 lanes in the first place. The Intel Alder Lake CPUs have the required Gen 5 lanes so it looks like the ASUS B660 might lack the necessary Gen 5 hardware on them to enable PCIe Gen 5 support. Now it isn't confirmed if ASUS is the only motherboard manufacturer that will lack Gen 5 support on their B660 lineup but it won't be the first time that this has happened with ASUS. ASUS's Z490 motherboard had a similar issue where the motherboards weren't outfitted with the necessary hardware to support the Gen 4 lanes on the then-new Intel Rocket Lake CPUs whereas the rest of the manufacturers had proper Gen 4 support.
For those of you who want to utilize the PCIe Gen 5 lanes in some way or form on the mainstream B660 motherboards should be aware that ASUS might not have that feature in place for their own lineup. We will keep you notified when we get more information regarding what other board AIBs are doing regarding Gen 5 support on their respective B660 motherboards.