First, I test with my E8500 and my E8400 the FSB with watercooling (same as aircool).
I was surpsised when I saw tha I reached 640Mhz on screen, and be able to do SuperPi 1M at 625Mhz.
I just give 1.42V to the NorthBridge, because more will decrease my FSB.
Then, I put my E8500 under my 2-Stages (made by Skrims-Fr).
In the first run, I reach 660*8 with my E8500. But, in touching CPU GTL, I just get 670MHz FSB !!!
Source : Xtremesystems