By BBC News Online's Ivan Noble at CeBIT 2002 in Hanover

A PC with its own refrigerator unit is the fastest in the world, its manufacturers say.

Running computers faster than they are designed to makes them overheat.

PC tuning enthusiasts have long used various tricks to cool their machines down and squeeze out that extra last bit of zip.

But the makers of the Vapochill PC, with an Intel processor clocked at 3 GHz, say their machine is the first commercially available computer to actually run at this speed.

Small and quiet

The computer has a cooling unit designed by a Danish company called Asetek.

It looks a little unwieldy, but is surprisingly small and quiet.

PCs that have been speeded up in some way are usually very noisy but this one is quiet

Pablo Valerio, Asetek

"PCs that have been speeded up in some way are usually very noisy but this one is quiet, quieter even than a normal PC," Asetek's Pablo Valerio told BBC News Online.

The cooling unit keeps the processor chip at 18 degrees below zero Celsius, far below the temperature of a conventional fan-cooled PC.

"It makes it more stable, too," Pablo Valerio said. "If you run a benchmark on a normal PC, leave it on for two days and then run it again, you'll find it's slowed down.

"That's because it has become hot, but our computer doesn't heat up."

Speedy processor

The Vapochill PC takes an off the shelf 2.2 GHz Intel Pentium 4 processor and speeds it up to the record-breaking pace.

PCs which have been "overclocked" in this way are often unstable, because the whole system, including the memory chips and the interface circuitry, is run well past its design speed.

But the Vapochill takes advantage of the way that some computer circuit boards are designed to speed up only the processor and leave the rest of the system unchanged.

The super fast 3 GHz PC costs about 6,000 Euros (�3,700) and is on display at the CeBIT 2002 technology fair in Hanover, Germany.