Bringing the Antarctic to the processor

David Field and Craig Simms do their part in a world record overclocking attempt.

Had you asked me 24 hours ago, I’d have told you I was a reasonably adept overclocker.

I was introduced to the sport many years ago, back in the days of the Celeron 300A. Since then I’ve tortured CPUs with the aid of water-cooling rigs and phase change units, and marvelled at Atomic’s own oil and dry ice cooled behemoth.

However, until yesterday I’d never had the chance to add liquid nitrogen -- or speed juice, as my overclocking buddies and I have for years referred to it -- to the mix.

That was before Craig and myself received an invitation from ABC2’s Good Game to be the judges of their overclocking challenge. We didn’t know the details, but assumed their resident tech, Miles “Dr Daneel” Tulett, had got his (as it turns out, highly skilled) hands on a phase change unit and was going to give a demonstration.

We burnt our benchmark suite to disc and jumped into a cab along with Nick Ross, who wanted to see what numbers the overclocked machines would spit out when faced with PC Authority’s benchmark suite. His money was also on a phase change system, guessing as we did that anything more insane would have the ABC’s occupational health and safety officials up in arms.

Our guesses as to what Good Game had planned were a long way off base. In fact, had we been in Antarctica, we would have been found 20 kilometres away from base, frozen to death.

They had brought in three nutcase overclockers attempting to break a world MHz record. We were greeted with an unreleased Core 2 Quad QX-6800; a vat of LN2 (Liquid Nitrogen, for the uninitiated) and a pile of safety papers when we walked into their studios. There was also a Celeron to be given the treatment for the fun of it.

The overclockers in question are Dino Strkljevic, James Turnbull and Kayl Hosken, and they’re a group of electronics engineers and meteorologists with a taste for cold, fast things.

Our job was to keep them supplied with speed juice, comment on the process and verify if they had or had not broken the world speed record.

Using LN2 is simple, in theory. Instead of transferring and removing heat from the processor, you take vast quantities of heat’s liquid kryptonite and unapologetically drown a processor in it.

As with anything of this magnitude, a few snags were hit on the way, but there were some creative methods around them. One of the many problems was the thermal probes in the CPUs wouldn’t register sub-zero temperatures, so guestimates were made based on thermal probes that had been strapped to the base of the pipes that contained the LN2, just above the processor.

The physics of transistors get fuzzy at -196 degrees Celsius, the temperature at which LN2 boils. The boys had to vary the LN2 and add water (which, like a mix of oil and water, sinks to the bottom of the LN2) to insulate the processor to avoid the “cold bug”, a point at which the processor temporarily gives up until you coax it back to life by raising the temperature.

Neither the overlockers or anyone else knows what causes the cold bug. That didn’t stop us from speculating though. I guessed that the semiconductors were exhibiting superconductive properties and losing the ability to switch electricity, being reduced to conductors in the process of being cooled to -190 degrees.

We now cross live to Craig Simms, from his desk 3 meters away, for his thoughts and speculation.

“People have had greater luck disabling three out of four cores on the quad while overclocking, which suggests that perhaps the bug has something to do with the interconnects between cores - even likely between pairs, since the QXs are essentially two dual core dies slapped on the one chip. Either way unlike single core, you now have to deal with the thermal properties of essentially four processors at once, which is going to raise complexity no matter which way you look at it."

It was all great fun, and I can now tell you that relative to these guys, I know very little about overclocking. I pause to think things through -- they run on instinct.

But naturally you want to know the results, and if we did indeed set the new world record. And those results are... not going to be revealed, because that would ruin the surprise. Also there’s that pesky legal thing. But you will see both us and the insanity unfold over the next few weeks on Good Game.

If you can't wait till then, you can always watch Logan being interviewed in the second episode of the second series.