Listing SQL Server instance startup parameters
In SQL Server 2008 R2 SP1 or later, this is made considerably easier via the sys.dm_server_registry DMV:

SELECT
    DSR.registry_key,
    DSR.value_name,
    DSR.value_data
FROM sys.dm_server_registry AS DSR
WHERE 
    DSR.registry_key LIKE N'%MSSQLServer\Parameters';


From: An easier way to get SQL Server startup parameters