AM5 PCIe speed limitation
AM5 PCIe speed limitation
I focus on different issues since the previous example had problems with the bottom x1 slot not functioning.
These issues stem from the boards themselves, not from the PCIe lanes in general. It could be that the boards are struggling due to excessive PCIe devices, which is the responsibility of the motherboard maker to confirm compatibility as described. This isn't related to a chipset bottleneck.