Hi there,
Ok, before I say anything, there's been a few people who've overclocked their CPU to 4.0GHz, with the help of some serious cooling.

I recently played around with one of my brand spanking new servers, my new toy, a P4 3.6GHz, I always had the 2.6GHz ones running at about 3GHz, all my servers have freezer cooling. Anyway, back to the point, I just decided to see what I could do, I ripped the sides off the case, and hooked up my freezer cooling, and put it in a single box, so it would be seriously cold, and shoved it in the air conditioning room.. I booted it all up, and tested how fast it could go, I had got it up to 3.8 no problems (woohoo!) and it was quite hot, about 10C, as opposed to 0, or just under, about -1. I decided to go for the big thing, it took me 3 tries, but I got it, 3 tries meaning 2 times failed - had to clear CMOS. On the third try I got it, 4.0GHz, it was running at an average of 40C, when I was doing the Pi test, but on general with server things, it was running at around 32C.

Of course I'm not going to offer hosting for it running on 4.0GHz, because I really can't predict if it might handle it all with the general stuff.

But yeh, wow 4.0GHz, I am so proud.

I use really expensive motherboards, of course I have hyperthreading on it. I was running linux, if it was windows, I wouldn't even reach 3.8 lol.

Anyone else have any cool stories playing around to share?

pentium is crap, get an amd dual core.

Care to explain?

I would never overclock a server, above all else you want a server to be stable and reliable. I have played around with overclocking regular PC's, using water cooling long before it was the "in" thing to do, adding peltier cooling to get the processor below 0c for serious overclocking.
What do you define as freezer cooling? Do you use a real phase-change cooling system (compressor etc.)?

Sounds like fun, it's also good to hear that you wont be trying to host customers on a over clocked server. Sure if you keep the over clocked computer cooled, it might be able to preform at that high of a clock rate for a while, but the chip wasn't designed to run at 4.0, so sooner or latter (defiantly sooner) it's gonna explode Some people will say over clocking is stable, however it's a fact that when they sell you a chip, it's intended to work at the suggested clock speed and only that clock speed. Anything higher and you risk stablity.