I've gotta hand it to the Extreme Edition 955 for one thing: it overclocks like a champ. Our sample would boot into Windows at 4.5GHz, although it wasn't quite stable thereit threw calculation errors in Prime95. The thing was rock-solid at 4.266GHz, though, with only a minor voltage increase. Now, mind you, I was using one of these things to cool it, but it still hit 4.26GHz on air cooling.
Intel, by the way, is now doing what AMD has long done with the FX series and making the upper multiplier on the Extreme Edition unlocked. I suppose if you pay $999 for a processor, they figure you should be able to have some fun with it.
Anyhow, the FX-60 wasn't as strong an overclocker, relatively speaking. It wouldn't boot into Windows at 3.0GHz, even with lots of extra voltage. At 2.9GHz, core 0 threw errors in Prime95, although core 1 seemed fine. At 2.8GHz, both cores were stable in Prime95 at 1.4V.