Comparison of PCIe lanes B450 and X470/X570 specifications
Comparison of PCIe lanes B450 and X470/X570 specifications
Currently using a Proxmox Server on a 3950X with dual NVMe drives, but two SATA ports and most PCIe slots are blocked except the first. An upgrade from your MSI B450 Carbon Pro to an X570 board would likely add more PCIe lanes without disabling the slots, which should help with GPU hardware encoding and RAID controller needs.
Consumer boards generally provide 20 to 24 PCI-e lanes, mainly due to the limitations of entry-level CPUs and the additional capacity from the chipset. For higher performance needs, switching to server-grade processors is necessary. Note: Sharing PCI-e lanes between SATA and M.2 devices on consumer hardware is typical and often unavoidable.
The interface available on an X570 board differs slightly between models, yet the overall layout remains consistent.
I don't require god team lanes, yet I'm unsure whether a B450 with 36/28 lanes versus an X570 with 44/36 lanes would suffice for my needs.
16 of these come always from the CPU for graphics... the remainder, if you're sure that many are supported by those chipsets, will originate from the chipset itself. Generally, 40 or more PCI-e lanes are considered top-tier and beyond what consumer-grade hardware like motherboards and CPUs can handle.
Verify your CPU compatibility with the planned motherboard. Check the available PCI-E lanes on both the CPU and the chipset. Find details on PCI-E lanes and SATA ports supported by each: https://en.wikipedia.org/wiki/Socket_AM4#Chipsets. Some manufacturers remove SATA ports to free up more PCI-E lanes—for instance, the B550 supports two extra SATA slots or swaps them for additional PCI-E lanes. X570 and X470 can split their x16 lanes into two x8 slots, though this depends on the motherboard maker’s design. Not every board offers this feature.
The chart isn't meant to represent the whole picture—check the specific CPU page for its limits. NOTE: For instance, Threadripper claims "support for 88 PCI-e lanes," which could exceed your needs, but you're aiming to run a server on non-server gear.
Thanks! You're right about Threadripper, but you're looking to work with the equipment you already own.
The CPU features 24 lanes: 1. Four remain dedicated to the chipset connection, leaving 20 PCIe lanes available. 2. Four lanes typically serve the first M.2 port. 3. Sixteen PCIe lanes are reserved for graphics. These can appear as a single PCIe x16 slot or two separate 8-slot configurations. The X570 chipset supports up to 16 PCIe lanes, though only eight are consistently available in standard slots. Additional PCIe lanes can be routed within the chipset to increase SATA ports (beyond the four always enabled) or to add more M.2 connectors. You might end up with combinations like 8 PCIe lanes plus two M.2 slots and four SATA ports, or swap four PCIe lanes for four SATA ports (8 PCIe + 1 M.2 + 8 SATA). The exact layout depends on the manufacturer's design choices. (Refer to the diagram for guidance on possible configurations.)