[bayindirh]

If your server is old, the RAID card's PCIe interface will be another bottleneck, alongside the latencies added if the card is not that powerful to begin with.

Same applies to your NVMe throughput since now you have the risk to congest the PCIe lanes if you're increasing line count with PCIe switches.

If there are gateway services or other software bound processes like zRAID, your processor will saturate way before your NIC, adding more jitter and inconsistency to your performance.

NIC is an independent republic on the motherboard. They can accelerate almost anything related to stack, esp. server grade cards. If you can pump the data to the NIC, you can be sure that it can be pushed at line speed.

However, running a NIC at line speed with data read from elsewhere on the system is not always that easy.