I tried these in my Chelsio T320 card and Intel X520-DA2 but I cannot seem get them to negotiate 1gbps I can get it to look like its working on the T3 card but it doesn't show the link up in Linux nor in a passed-through windows VM. I do not have another 10gbps BASE-T interface to try to connect to so I'm not sure if it works or not. One thing of note, when it's plugged into the NICs not doing anything it gets pretty hot, almost to hot to touch.