No, PCI-E 4.0 is not disabled in the AMD B450 or Intel H410/H510.
No, PCI-E 4.0 is not disabled in the AMD B450 or Intel H410/H510.
No, PCI-E 4.0 is not disabled in the AMD B450 or Intel H410/H510.
This approach focuses on removing features that are rarely used. The b550 is the only budget board with a PCIe 4 port, though it only has one slot.
It relies on the specific board design and CPU configuration. Note: Based on a quick search, the PCIe lanes from the chipset (not the CPU) are pcie2 on B450.
The option to disable it isn't the simplest solution. For B450 models, it wasn't a necessity at launch, meaning not every board can handle PCIe 4.0. With H410 and H510, it's probably not feasible since they're mostly budget-focused designs. The discussion refers to the slot linked to the CPU, while X570 is the only one supporting PCIe 4.0 directly on the chipset.
It's not clear but you can see where it came from. Some B450 boards at one time supported PCIe 4, but because it's only "some" it has been causing confusion and resentment from brand with few or even no PCIe 4 capable B450 board so AMD unified the situation by not allowing PCIe 4 on all B450 motherboards. If OP also considers the chipset, then B550 and all Intel chipsets have disabled PCIe 4 as well