question

I suspect that going back through the history of your monitoring application (if you have one) will be your best bet. If you need something a bit nearer to the present, this query might help (Nicked from Benjamin Nevarez - read the rest of his blog post [Getting CPU Utilization Data from SQL Server][1] for a more details and another friendlier query): SELECT timestamp , DATEADD(ss, ( -1 * ( ( cpu_ticks / CONVERT (FLOAT, ( cpu_ticks / ms_ticks )) ) - [timestamp] ) / 1000 ), GETDATE()) AS EventTime , CONVERT(XML, record) AS record FROM sys.dm_os_ring_buffers CROSS JOIN sys.dm_os_sys_info WHERE ring_buffer_type = N'RING_BUFFER_SCHEDULER_MONITOR' AND record LIKE '% %'; But it only goes back four hours or so. [1]: http://sqlblog.com/blogs/ben_nevarez/archive/2009/07/26/getting-cpu-utilization-data-from-sql-server.aspx