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Record Attempt: The 5 GHz Project, Continued

5 GHz Project: CPU Cooling With Liquid Nitrogen

Only liquid nitrogen can produce ideal processor cooling - in this case from our 25 liter transport container.

Experience gathered in past investigations told us that these kind of clock rates can only be achieved on the P4 platform. Nonetheless, as we prepared for each test, we had no clear idea which clock rates would be reached in conjunction with selected components. Our last speed record is exactly a year old. Then we succeeded in getting an Intel Pentium 4/3.06 to operate stably at 4.1 GHz. A few days later we showed how an AMD AthlonXP works at 2.8 GHz. The basis for these tests was a powerful compressor cooling system from Chip-con with a few modifications. Ten months later, with the same basic configuration, we managed to overclock the first 64 bit processor on the desktop market - the AMD Athlon64 FX. The end of the flagpole was reached at 2.8 GHz. Anyone really interested in extreme overclocking should read the following articles :

An image from the preconditioning phase : it was by no means certain which clock rate we’d eventually reachAn image from the preconditioning phase : it was by no means certain which clock rate we’d eventually reach

Extreme Heat Dissipation : 1600 KW Per Square Meter !

Nothing produces as much heat dissipation per square meter as a modern processor. There is certainly nothing in everyday life to compare it with. In the case of our Intel Pentium 4 (the 3.2 GHz version in our example), whose die surface comprises 112 square millimeters, the heat dissipation is up to 84 watts at maximum load. In plain English : 84 watts on a surface of 1.12 square centimeters - the size of a fingertip ! Extrapolated to square meters that make 840,000 watts or 840 kW. As a point of comparison : a good household iron has maximum heat output of 2,000 watts and emits this over a surface of approx. 200 square centimeters. That adds up to 10 watts per square centimeter. Our regular 3.2 GHz P4 CPU radiates more than eight times this thermal output.

Heat dissipation rises exponentially during extreme overclocking In the past we recorded about 135 watts using the Chip-con compressor at 4.1 GHz. Using our nitrogen cooling to break the 5 GHz sound barrier would produce peak heat dissipation of up to 180 watts emitted from a die surface area of 1.12 square centimeters. Applied to our example that means 1,600,000 watts, 1,600 kW or 1.6 MW per square meter. By this point it must be clear how important efficient processor cooling is. But with simple means there is no way around the problem. Compared to our past extreme overclocking tests, requirements on CPU cooling have risen enormously.

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