Modern connections using PCIe 4.0 lanes can work with older PCIe 3.0 devices.
Modern connections using PCIe 4.0 lanes can work with older PCIe 3.0 devices.
I've encountered similar inquiries before, though I haven't found a definitive solution. If you have a motherboard supporting PCIe 4.0 and a CPU with 20 lanes, using four lanes for storage is feasible. You could opt for two Gen 3 SSDs instead of one Gen 4, staying within the four-lane limit. While two Gen 4 lanes can handle any Gen 3 4X SSD at peak speeds, the compatibility depends on the specific motherboard design. Some models permit this configuration without affecting the remaining lanes used by other components. A straightforward yes or no would suffice, but technical details are welcome as well.
Uh 4th Gen Ryzen motherboards aren't released or even reviewed yet. (600 series chipset) So no one can answer this question.
The slots are compatible with version 3.0, and you'll require eight lanes for them to function properly.
You're referring to 400 series motherboards built for Zen+ 2000 series chips? Got it. The GPU won't cause PCIe 3.0 saturation, so most drive setups should work fine. You're free to proceed without issues. There are plenty of lanes available. (unless you're running several cards, as noted earlier.)
It suggests that with sufficient bandwidth in the motherboard lanes, a basic switching system for lane allocation could handle many PCIe 3.0 devices, including two GPUs and two NVMe SSDs.
It relies on the specific design of the motherboard. You might connect 3.0 SSDs into x4 4.0 slots, but you'd lose 8 lanes overall since they operate at 3.0 speeds and wouldn't be able to use the extra capacity. Alternatively, you could use PCIe bridges that you can set up manually based on available connections. There isn't a universal yes or no answer for all boards. I don’t seem to have noticed any M.2 slots sharing lanes like that with other M.2 or PCIe ports, though I’ve seen some boards handle lane management between certain PCIe slots. The best scenario appears to be inserting an expansion card into a 4.0 x4 PCIe slot that also has two M.2 3.0 slots.
These useful images are commonly available online, showing how PCI-e lanes are organized. For the X570 model, you have 16 lanes dedicated to graphics, which is quite unusual and could be repurposed for other uses. There are also 4 lanes reserved for storage devices, plus an extra 4 lanes for the chipset. It's worth noting that the chipset actually supports up to 8 PCI-e lanes, mainly due to Gen 3 specifications. PLX chips are mentioned earlier, but their availability depends on the motherboard.