AMD Phenom II overclocked with liquid helium

The Coldbug is the point where the CPU quits to work because of too low temperatures. The Coldbug temperatures of the Phenom I were 0 and minus 40 degrees Celsius, while Intel's CPUs of the pre-Core i7 generation were working at minus 150 degrees Celsius and even below. The lower the temperature of a CPU is, the smaller the leakage currents inside the CPU. Those currents can result in miscalculations and fatal CPU damages. If the core voltage is increased, the amount of leakage currents is increased exponentially. Therefore Intel had an advantage in matters of overclocking, just because their CPUS could endure lower temperatures.

When developing the Phenom II, AMD tried to get rid of the Coldbug. To demonstrate that the Coldbug had been extinct, AMD invited three first-class overclockers from Finland - "Macci”, "Sampsa” and "SF3D”. The three had access to 120 CPUs for their experiments. Three samples that ran with more than 6 GHz during spot tests with liquid nitrogen had been chosen for the demonstration. Besides the Phenom II 940 Black Edition with an open multiplier, Team Finland used a DFI 790GX board, 4 GiByte memory from OCZ and two Radeon HD 4870 X2. To cool the CPU several containers had been available; the F1 EE of the overclocker "K|ngp|n” was used for the demonstration.

At first the three overclockers brought the system to minus 196 degrees Celsius with liquid nitrogen. After that the liquid helium, which has a temperature of minus 267 degrees Celsius, was injected into the container. But when this is done there must not be any remains of liquid nitrogen in the container because it would freeze instantly. The smother that forms when the helium is injected, is huge - as you can see on the pictures in our gallery.

The test setup was running Windows stable at minus 242 degrees Celsius and could even be booted at minus 245 degrees Celsius. Compared to liquid nitrogen, the lower temperatures resulted in a boost of about 150 MHz. On workload the temperature increased to about minus 216 degrees Celsius. When the overclockers wanted to attach the containers for liquid nitrogen cooling to the graphics cards, they encountered problems and thus they actually used the HD 4870 X2s on air cooling only.

During the demonstration, Team Finland focused on 3DMark 05 and was able to reach a new peak after two hours, which was the highest value recorded in the Futuremark database at that time. But the French "boblemanifique” was able to reach a 1,000 points higher result on January 5th with a Core i7 based system. Thus Team Finland was not able to reach a new world record.

But the question if AMD was able to get rid of the Coldbug can be answered with a clear Yes. The Phenom II 940 BE ran the benchmarks at 6.3 GHz, for CPU-Z 6.5 GHz were stable, a impressive result since the predecessor rarely exceeded the 4 GHz limit. AMD had filmed the event so a video should be available soon. In our gallery you can find some worth seeing pictures.

Other articles related to the Phenom II:
• Phenom II retail version and boxed cooler pictured
• AMD Phenom II X4: Deneb reviewed
• AMD Phenom II: Overclocking with dry ice