So you have a IIS Webserver that is running at 100% cpu and the process causing this is w3wp.exe, this is a good way to find out which App Pool / Site is causing the problem.
- Create a shortcut with the following command & save as List_IIS_Apppools.cmd
%windir%system32cmd.exe /k iisapp.vbs
- Run List_IIS_Apppools.cmd
- Download and install Process Explorer here – http://technet.microsoft.com/en-us/sysinternals/bb896653.aspx
- Run Process Explorer and sort by CPU or Memory (depending what is being hammered)
- On the w3wp.exe that is taking the most resource (highest %) note the PID number down and compare to the App Pools list from List_IIS_Apppools window.
Now that you know the App Pool which is taking all the resource you can Recycle and troubleshoot.