Adding a rowversion column is not related to snapshot isolation levels. In snapshot isolation concurrency is increased by taking a snapshot of the data you need for your transaction and putting it in tempdb instead of locking that data from other users. Your transaction uses the snapshot stored in tempdb, if you make changes and try to commit them after someone else has changed the same data your transaction will fail. See this article, http://msdn.microsoft.com/en-us/library/tcbchxcb(v=vs.110).aspx