Have you considered Netperf? I know many of Solarflare's customers are using that. You should be able to test server to server with a standard twinax DAC between cards. As for the SFN5122F that is one of our lowest latency cards, however the kernal bypass middleware (OpenOnload) for that currently will only run in a linux environment. For Windows I would suggest one of our performant level cards such as the SFN5162F,which also has very good latency.