For those of you who have a Kentsfield and want to test high FSB you can disable corew three and four to reach the highest bus speeds possible on your motherboard.
I wanted my bandwidth back and dropped to one core and went for 500FSB and it booted, then enabled core two and the system booted into windows fine.
This will improve scores that dont take advantage of four cores/threads with the maximum FSB being possible as well as a small increase in the top speed of the chip when running only two cores. I cannot confirm that all systems will work as described above, I am on an 680i board by EVGA that will go past 500 with ease.
This is for benching and for those who want to try it.