Buyer Beware: Certain AMD Ryzen B550 boards are stripping off PCIe 4.0 for only PCIe 3

At its Computex 2022 event, AMD's CEO Dr. Lisa Su confirmed that the now five-year old Socket AM4 will still be around for a while. While that is indeed a praiseworthy move, it looks like buyers will still need to be careful when purchasing a new AM4 motherboard.

That's because certain B550 chipset motherboards are dropping PCIe 4.0 support in favor of just PCIe Gen3. The MSI PRO B550M-P GEN3 model is one such motherboard as spotted by Twitter user MEGAsizeGPU:

AMD introduced PCIe 4.0 support with its 500-series motherboards and both the flagship X570 and the mainstream B550 chipsets have officially been specced to support PCIe Gen4. Only the entry level A520 chipset does not support the 4th Gen PCIe standard.

The spec sheet of the MSI PRO B550M-P GEN3 motherboard confirms that PCIe 4.0 support is missing on these boards:

We looked around and found other MSI boards labelled as "Gen3" which are only PCIe 3.0. For example, here is the spec sheet of a B550 GAMING GEN3 model which also lacks PCIe Gen4:

While most graphics cards with the full 16 lanes or even 8 lanes should not be held back by the throughput provided by PCIe 3.0 (8Gbps), storage devices can be handicapped greatly as NVMe technology is moving forward really fast with PCIe 5.0 stuff already lined up for release in the very near future alongside Socket AM5.

The good thing about these boards is that MSI has clearly indicated that these boards are PCIe 3.0-only; but other motherboard vendors may not make the distinction as clear. As such, it is advised to visit the official website of such vendors and confirm whether a board comes with PCIe 4.0 or not.

This isn't the first time a B550 chipset has been spotted lacking PCIe 4.0 support. Earlier, AMD's OEM partners were using a certain "B550A" chipset in Ryzen pre-builts. At the time, Robert Hallock, Director of Technical Marketing at AMD, revealed that the B550A was actually based on the previous 400-series chipset which had no official support for PCIe Gen4.

Buyer Beware: Certain AMD Ryzen B550 boards are stripping off PCIe 4.0 for only PCIe 3