AMD Ryzen processors support PCIe lanes for enhanced connectivity options.
AMD Ryzen processors support PCIe lanes for enhanced connectivity options.
Hey, this is a topic im very confused about. How the hell do the PCIe lanes work on amd ryzen. Im planning to upgrade to a Ryzen 7 2700X with a B450 Tomahawk MAX motherboard. I use 3 drives ( 2 sata SSD's and 1 HDD). I also want to use two gpu's. an RX 580 for gaming and a gtx950 for computing. Ryzen 7 2700x has 20PCIe lanes, which would allow me to use 2x8 for the GPU's and have 4 more free, and here are my questions: 1. will i be able to install an NVMe later on? 2. why do mobo manufacturers make their motherboards with so many pcie lanes when the CPU's cant cover them all ( not even a 3950x ) 3. do the SATA3 storage devices even take up CPU pcie lanes, or are they handled by the mobo? Sorry for the dum questions. Edit: I found this diagram on the net, however i dont understand it Edited May 20, 2020 by strikeq535
CPU features 24 PCI-E lanes. One lane serves video cards, two go to the M.2 connector, and four connect to the chipset. Depending on the chipset, the video lane allocation may vary—some support splitting into two 8-lane PCI-E slots. The X470 chipset allows this, as does the B550, while the X570 supports 8 lanes. You can connect a gaming video card to the PCI-E x16 slot. The computing card fits into the chipset’s PCI-E x4 port, maintaining performance despite fewer lanes.
This illustration applies to X570 and earlier models. Notice how SATA exits the chipset lanes, not the CPU lanes.
The setup remains unclear. Using the x4 from the chipset for a GPU doesn't necessarily restrict SATA3 ports or NVMe, but you should verify compatibility with your specific hardware.
Not on the B450, only X servicing boards allow splitting the X16 from the CPU. The M.2 slot offers its own lanes, and since the chipset manages its own lanes, many devices such as Ethernet cards don’t require full bandwidth. It depends on the port—some come from the CPU, others from the chipset.
It depends on the motherboard design. In the diagram, the bottom middle area displays various choices for the 12 flexible PCIe lanes: 3x4 NMVe, 2x4 NVMe, plus 4 SATA and 8 SATA. To be clear, four lanes are reserved for the chipset and cannot be selected differently.
The chipset functions as a PCIe switch, allowing you to utilize the connection alongside SATA and other PCIe devices connected to it.