Z490 PCH supports SATA and PCIe lanes.
Z490 PCH supports SATA and PCIe lanes.
Today I discovered: The Z490 lacks dedicated SATA ports and shares them with PCIe lanes. I assumed it had its own SATA port. It actually has six USB 3.2 Gen 2 ports and four USB 3.2 Gen 1 ports that overlap with four PCIe lanes. The Z490 PCH supports 24 PCIe lanes, but if we allocate four USB ports and four SATA ports, only 16 PCIe slots remain for other devices. Fascinating. Another point is despite having 24 PCIe lanes, it can only accommodate 16 devices. Curious about the DMI 3.0 bandwidth next.
Regards, Chiyawa
There are dedicated PCIe lanes for SATA devices. For other connections, additional components are required to convert them into SATA interfaces, such as the ASM1061 chip. Unlike AMD, Intel provides these specific lanes without needing extra hardware if you're aiming for a bare-SATA setup. Only six USB ports remain fixed; if you consider all PCIe lanes as 30 instead of the usual 24, there are just six more lanes available for manufacturers to arrange freely on the motherboard.
I noticed several manufacturers offering the high-end Z490 motherboard, but it appears to be missing most of its PCIe lanes. That caught me off guard since SATA is treated like a PCIe lane in the Z490, and only a few boards provide just eight SATA ports—they simply don’t have enough slots left. I was also puzzled about why many M2 slots share lanes with other devices; it seems unusual given that 24 lanes should be fully available. Probably I wasn’t expecting such configurations...
USB 3.2 Gen 2 x 1 offers 10Gbps speed, while PCIe Gen 3 tops out around 7.88Gbps. It seems they excluded PCIe lanes from the chipset because it supports Gen 3. AMD handles SATA and PCIe separately, making the distinction clearer. Intel’s documentation didn’t explicitly mention shared ports until you reviewed their spec sheet. That actually surprised me.
unfortunately you don't usually find such records on amd sites. there are indeed limitations on pcei distribution. as shown in the image, 24 pcie slots are organized into sets of four. mobo designers can't use pcie numbers 19, 20, 21, or 22 for gen3x4 m.2. some examples include 1234, 5678, 9101112, 13141516, 17181920, 21222324. this explains why certain m.2 cards need to share lanes with sata, and look at pcie #9, 10, 11, or 12—these four slots could serve as a 1*m.2 (gen3x4) unit or accommodate two sata interfaces.
PCIe grouping refers to how Intel organizes its PCIe lanes, and it can vary depending on the chipset. The AMD X570 uses a similar concept, though details for B550 are unclear. Their layout allows flexibility, like using SATA 0 until 8 lanes alongside PCIe 17 up to 24, and GbE sharing with PCIe 17 or 18, enabling multiple configurations. It's interesting how Ethernet controllers are embedded in the PCH yet still require a dedicated PCIe lane for connectivity.