Just to be sure...
Just to be sure...
I understand if this seems like an overly simplistic question, but I haven’t really considered it closely before it popped up... However, if you have a motherboard with a chipset built around PCI-E 3.0 and the 16X port connected to the CPU, while keeping the same mechanical layout between generations, upgrading CPUs that span different PCI-E versions—like from Zen 1 to Zen 3 (or even 4.0)—you won’t suddenly see PCI-E 4.0 on the x16 or NVMe M.2 slots, right? I’m guessing not. I know there are other changes between generations, but mechanical compatibility keeps that idea out of my mind. The chipset likely stays the same unless you swap the board. Also, yes, the x16 3.0 bus won’t see a big jump; scaling in the 4090 shows maybe a slight drop of around 3%.
I only consider this idea because the top x16 and M.2 act as direct connections to the CPU. Maybe just hoping it works!
The shielding requirements for PCIe4 are significantly more stringent than PCIe3, which might indicate an interference issue. While some motherboards provide the necessary shielding, they often restrict it through software settings. In theory it could function, but in practice it doesn't. Asrock has permitted certain PCIe3 boards to support Gen 4, though AMD likely tightened restrictions afterward.
The issue isn't about the chipset itself but comes from BIOS settings. AMD supplies core modules to motherboard makers, who then integrate their components. Even though newer chips support PCI-E 4.0, the boards must be built to handle it without errors. Higher-quality PCB materials are needed to protect fast signals on the board, and routing between PCIe slots and CPU sockets demands stricter standards. Sometimes manufacturers upgrade from a 4-layer to a 6-layer board just to maintain signal integrity at 4.0 speeds. Wire lengths between CPU and PCIe devices must be kept short; otherwise, buffers are needed to boost signals. Some boards moved from 4 to 6 layers solely for this purpose. Additionally, maximum wire lengths are limited, so if they exceed a threshold, amplifiers or re-transmitters are added. There were cases where older chipsets managed 4.0 well, but newer models struggled with error rates, risking temporary PCIe 3.0 operation before switching. This inconsistency led to frustration, with users blaming AMD for reliability problems. Another concern was inconsistent BIOS updates—some boards enabled 4.0 while others didn’t, creating confusion and prompting complaints about manufacturer support. Ultimately, to avoid confusion, the industry decided to restrict PCI-E 4.0 support to higher chipset models like B550.
Finished swapping the CPU. Everything looks okay. I'm doing a light adjustment to let it warm up properly. Interesting note in CPU-Z since we mentioned PCI-E before. The software shows mainboard handling bus data for PCI-E 4.0 when the CPU is installed (under mainboard section, not CPU). It's definitely getting that from the CPU itself, not the board or chipset. GPU information matches correctly as PCI-E 3.0.