Check compatibility with PCIe 4.0 x2 slot.
Check compatibility with PCIe 4.0 x2 slot.
Connect the two machines with Intel XL710-QDA2 cards using PCIe 3.0 x8 slots. Your MSI x670-P board only has a PCIe 4.0 x2 slot, which is larger than the required size. The diagram shows "PCI_E4" for compatibility. If your other computer uses a PCIe 3.0 x16 slot, the connection should work and you’ll likely achieve speeds around 10 Gbps, though the actual rate may vary based on the specific cards and configuration. Your previous test with Mellanox cards showed higher performance in PCIe 4.0 x2, so this setup should be feasible.
Because it uses a PCI-E 3.0 x8 interface, it operates in PCI-E 3.0 mode when connected to your PCI-E 4.0 port. This means the PCI-E slot will only support up to about 2 lanes, resulting in a maximum bandwidth of roughly 1.9 GB/s—well under the 16 Gbps limit.