Thanks for your response. I got the result of sp_who2 when the CPU usage was high. In that I could find that three IIS servers are connected to the server and the the SQL server is awaiting command for a long time from each IIS servers.will this be a reason for the high CPU usage.
Please find the below commands and CPU usage

AWAITING COMMAND 274085 69 01/04/1930 14:15 .Net SqlClient Data Provider
AWAITING COMMAND...

SQL server is runing at 80% of CPU utilization. There are some issues with the front end application that connects to this server.
1.Application fault - a database browse is retrieving all records from a table, rather than a subset
2.Archiving – data is not being archived so building up, presumably exacerbating issue 1).

will this be a reason for high CPU usage.

I dont have access to this server. But...