How to Clear SQL Server Cache When Performing Benchmark Tests

I was testing the perfomance of a query from different perspectives and wanted to make sure SQL Server didn’t cache Query results, to achieve this:

run DBCC DROPCLEANBUFFERS, which clears all data from the cache. Then run DBCC FREEPROCCACHE, which clears the stored procedure cache.
 

found at:

http://www.devx.com/tips/Tip/14401