This program does not run by command line, but it
does seem to be the most accurate one I've ever tested.

WCPU_ID v3.1
Home Page: http://www.h-oda.com/

If you have trouble downloading you can try these links as well:
http://my.vector.co.jp/servlet/System.FileDownload/download/ftp/0/38172/pack/win95/hardware/cpu/wcpu310.exe

http://hp.vector.co.jp/authors/VA002374/src/download.html#wcpu

Here is the INTEL links for their program

The Intel Processor Frequency ID Utility
http://support.intel.com/support/processors/tools/frequencyid/

Download for DOS based v4.61 version of ID Utility:
http://downloadfinder.intel.com/scripts-df/proc/T8Clearance.asp?url=/3088/eng/bfid_e17.exe

Download Windows based v4.61 version of ID Utility:
http://downloadfinder.intel.com/scripts-df/Detail_Desc.asp?strState=LIVE&ProductID=49&DwnldID=3084