I’m looking for a 10Gb PCI-e card for a PC to connect via SFP+. I’m not intimately familiar with the connectors/protocols, but I’m seeing a number cards with QSFP+ (or mixed QSFP+/SFP+) connections on eBay that are the same price as (or cheaper than) the SFP+ cards. It’s simple enough to get a QSFP±to-SFP+ convertor for now, so other than the extra cost of the converter, is there any reason to not get a 40Gb QSFP+ (or mixed QSFP+/SFP+) card so that it would also be compatible with the faster speeds if they get some infiniband gear in the future?
It depends of if you have a switch that supports it. FS.com has an ex plainer here
SFP vs SFP+ vs SFP28 vs QSFP+ vs QSFP28, What Are the Differences? | FS Community