If you need to find out if a SQL Server instance has ForceEncryption turned on at a server level the only reasonable way to do this is read it through the registry. You must look for:
- SOFTWARE\Microsoft\Microsoft SQL Server\
May I also note that at least for SQL Server 2008 R2 where there’s the DMV for reading the sql server config in the registry sys.dm_server_registry this value is not tracked. You must resort to using xp_regread.