You can connect up to four NVME x4 drives to the Z390 at full speed.
You can connect up to four NVME x4 drives to the Z390 at full speed.
Your setup allows for two NVMe X4 drives. When you connect them, the total bandwidth will be split between the two, effectively halving each drive's speed. The line count remains consistent but the performance per drive decreases.
Without a GPU you can execute them at maximum performance or configure the GPU for x8 (minimal impact on speed) to achieve full speed. If available, the chipset offers 24 PCIe lanes; a GPU consumes 16 lanes, suggesting you might allocate 8 lanes for your NVMe drives, though additional traffic uses other channels. Only one M.2 can operate at full speed with a GPU in an x16 setup, while the remaining will be restricted to x2.
The m.2 slots and the GPU operate independently, each drawing power from the chipset lanes. You can use both drives at PCIe x4 speeds, though performance may be limited by the chipset connection. Overall, there’s only 32 Gbps available to both storage devices, which is unlikely to cause a problem.