If you want to speed up your PC, head for the fridge

OPEN the fridge door this Christmas and you could be straying into a battle zone. The sausage rolls are under siege and the turkey's turned chicken, shoved aside by an arsenal of pipes, pumps and water tanks. Aunty's trifle has surrendered to wires and circuit boards that look suspiciously like the innards of a computer. The overclockers are invading-and the last thing on their minds is your Boxing Day buffet.

Overclockers are computer enthusiasts with a taste for speed. They spend every spare moment supercharging their machines and, with a bit of fiddling, they can run them far faster than the manufacturers ever intended. Victory means blistering games performance, massive number-crunching power and kudos with their mates. Yet most do it simply because they love to tinker. "Part of the fun is figuring out how to make it go as fast as possible," admits Andrew Brown, the overclocker behind www.Tech-Report.com.

Successful overclocking doesn't come easily: it can take hours of testing, a kitchen full of plumbing gear and litres of chilled water. As if that's not enough, a few hard-core speed freaks have opted for the ultimate in overclocking-the finger-freezing thrills of liquid nitrogen.

Souping up a sluggish PC is simple, at least in theory. The speed of a processor-Intel's Pentium chip, for example-is controlled by an internal clock, a circuit that pulses millions of times a second. The faster it ticks, the quicker the processor works through its tasks. If you can speed up the circuit by raising the voltages applied to the chip-"overclock" in tech-speak-you gain a faster processor for the cost of a slower one, the performance of a hot rod for the price of a family saloon.

But a faster clock means more current pumping through the processor. All those extra electrons churn out a lot of additional heat, and if it isn't siphoned off pronto, the chip will fry.

These days the processor in your PC comes ready cooled with a small fan and a set of metal fins called a heat sink stuck to its back. But these dainty components can only expel a trickle of heat, so most overclockers start by replacing them with bigger ones. Then they raise the clock speed until either the processor overheats or the computer crashes. But to push the processor further-to double its speed, for example-you need more. One solution is to roll up your sleeves and turn plumber.

The idea is to get cold water as close to the processor as possible. So off comes the fan and heat sink and on goes a heat exchanger, a hollow block of metal with a pair of nozzles sticking out of the top. Now clear some fridge space-Christmas is a tough time for overclockers' families-and pop in a tank of water. Connect the tank and heat exchanger using hoses or copper pipes, add a pump and you can circulate the icy water past the hot chip and back to the fridge. With the heat dispersing nicely, overclocking can begin in earnest.

Almost every overclocker's rig is different. Some build mammoth water-cooled systems with car radiators and huge fans to extract the heat. Others avoid water altogether and use Peltier coolers, electric devices that shift heat away from the processor. Overclockers in Canada have been known to simply pump winter air from outside into their computer cases. A few have even relocated their entire computer into the fridge.

Whatever the system, overclockers gather on the Internet to discuss tactics, offer advice and share triumphs or disasters. "If someone discovers something Monday, the overclocking world knows about it by Tuesday," says Ed Stroligo, editor of www.overclockers.com. Like the time American overclocker Tom Leufkens discovered his processor frozen in a block of ice. (Suggestion: switch off your cooler from time to time). Or the Australian who found that his plumbing had been invaded by a clingy, green, algal goo. The solution to this came from James Rolfe, speed fiend and editor of www.overclockers.com.au: "A bit of cheap vodka in the water."

If alien slime setting up home in your computer sounds bad, surely the potentially volatile mix of water and electricity is far worse? Don't you believe it, says Rolfe: "I've never heard of anyone getting more than a fright." Instead, many agree that the real demon is moisture in the air: it can coat a cold processor with frost in minutes or create condensation that will turn connections to rust.

The danger of damp has driven one or two overclockers to extremes. A few years ago, Eric Caward, alias Dr Ffreeze, a computer technician from Boise, Idaho, attempted the ultimate fix. He extracted the motherboard-the circuit board that carries the processor and memory chips-from his PC and sat it in a polystyrene box. Then he flooded the whole thing with ice-cold mineral oil and switched it on. Dr Ffreeze's submerged system turned out to be a surprising success. Since the oil is an insulator and also repels water, the connections remained dry and the processor stayed healthy-even at -40 °C.

Dr Ffreeze's efforts have inspired others in the ultimate quest for cool. In June, New Zealander Ramil Tranquilino embarked on one of the most serious overclocking missions yet. He submerged his motherboard in an insulating oil called fluorinert and began to pump the oil through a reservoir cooled with liquid nitrogen. However, the oil got so cold that it solidified, the pumps clogged up and the experiment failed.

But instead of giving up, Tranquilino concocted an even more ambitious plan. In September, he submerged his motherboard in fluorinert, this time cooled directly with dry ice and liquid nitrogen. Since he wasn't pumping the fluorinert through pipes, it didn't matter when the stuff solidified. By the time the processor reached -42 °C, he had doubled its speed. Then he turned on his secret weapon: a heat exchanger filled with liquid nitrogen.

In seconds, everything had frozen solid and the thermometer registered -150 °C. Success. Then the monitor started to flash strange images. Pressing keys on the keyboard produced random characters on the screen. "In other words," Tranquilino says, "the motherboard was stuffed."

It's not unusual for overclockers to lose a battle or two on the road to victory- it's all part of the challenge. Tranquilino is already planning his next campaign. "Next time," he says, "I'll be shooting for total liquid nitrogen submersion." It might seem a bit extreme for a morsel of extra speed. But at least it'll keep him out of the fridge.

Ben Crystall