I've been trying to do some scalability testing on SQL 2012 Enterprise edition (from MSDN - no Key required). After wondering why I couldn't use all the CPU, I found the issue that Enterprise+CAL is limited to 40 threads (20 cores). I'm assuming this is my problem... I do see schedulers > 40 as "VISIBLE OFFLINE" in SQL and I have this in the SQL ERRORLOG:
2013-09-11 23:35:25.51 Server SQL Server detected 2 sockets with 12 cores per socket and 24 logical processors per socket, 48 total logical processors; using 40 logical processors based on SQL Server licensing. This is an informational message; no user action is required.
I'm just using the MSDN version, so I can't plug in a license key like this recommends:
http://blogs.msdn.com/b/sql_shep/archive/2012/06/21/sql-server-2012-license-core-limitaion.aspx