Check CPU throttling. Disable it in the BIOS so the OS can't mess with it.
This will get you started in the right direction - speed step: disable
Google search: windows 7 cpu throttling
http://www.google.com/search?hl=en&a...i=&safe=images
http://www.sevenforums.com/hardware-...hrottling.html
http://www.overclock.net/windows/503...hrottling.html
http://www.overclock.net/intel-cpus/...s-jumping.html
http://social.technet.microsoft.com/...2-d87965fd6592
Google search: windows 7 cpu throttling disable
http://www.google.com/search?hl=en&l...&aq=f&oq=&aqi=
http://www.tomshardware.com/forum/25...dstep-disabled
* http://74.125.155.132/search?q=cache...&ct=clnk&gl=us