Intel Pentium 4 3.2Ghz Extreme Edition Northwood Processor @ Tweaknews
But even so, say you still have a little overclocker left in you and want to see what extra cycles you can squeeze out of your new purchase, with some decent air-cooling you could easily overclock it above 3.6Ghz. Now I know if I had a water-cooling or a refrigeration setup, 4Ghz wouldn't be far out of reach. I personally can't wait to reach this goal.