I'm setting up a new system and I'm trying to wrap my head around how PCIe lanes work, especially concerning my components. I've got a 9800x3d processor on a Gigabyte B850 AORUS Elite Ice motherboard, paired with a 9070XT graphics card, three M.2 drives, and a Seagate Barracuda HDD. The M.2 drives are plugged into M2A_CPU, M2B_CPU, and M2C_SB. I know my CPU has 24 PCIe lanes available, but I also read that the chipset has its own lanes. Will the connections for the M.2C_SB and the SATA HDD affect the lane availability for the other components? Am I understanding this correctly?
1 Answer
Here's the breakdown: AM5 CPUs actually have 28 PCIe lanes total, but only 24 of those can be used directly. The remaining 4 are dedicated to the chipset, which handles connections like SATA, USB, various M.2, and other PCIe devices. So, your M2C_SB and the SATA drive don’t hog lanes from your CPU; they operate through the chipset and the 4 PCIe lanes it uses to communicate with the CPU. This setup should ensure your GPU and NVMe drives maintain their performance. If you swap your boot drive to the chipset M.2 slot, you might see a minor difference in speed, but most users won't notice unless they’re doing heavy data transfers regularly.
Got it! So, the GPU will still get its full x16 bandwidth even if I switch things around. Just making sure I don’t hit any performance bottlenecks with my setup!