Overclocking in theory..

[Johnny Bravo]

In fairness Sampsa I'm more impressed that the AMD still functioned as a cpu at those temperatures! A few things to note:

• Lower temperatures = lower resistivity. Lower resistance allows for more current to pass along a given cross section of copper
• Switching Frequencies. When a transistor switches there are losses involved in the form of heat etc so as you up the frequency you up the heat load from switching and heat = increase in resistance resulting in more losses
• Exotic materials properties at cryogenic temperatures. I've no idea what AMD are currently using in their silicon lithography processes these days but the electrical behavior of materials at cryogenic temperatures can be remarkably different from that at room temperature.

Another thing is as we increase these frequencies into the GHz the usual digital on/off square wave basically turns into an analogue wave as the ability to charge/discharge the capacitive load fast enough to get a straight edge just cannot to achieved. I'd say the circuits ability to distinguish this level change will also dictate an upper limit to frequencies.