The Hyper-Threading technology that Intel uses in its Pentium 4 and Xeon processors makes a single processor work as two virtual processors, so the Pentium 4 in your PC appears to have two CPUs while a dual Xeon workstation has four virtual processors.

The technology works very well, providing plenty of processing power relatively cheaply, but there is a fundamental problem as the processor is working very hard and that takes a lot of power and also generates a lot of heat. This isn't a new problem and the processor manufacturers have faced it a number of times over the years.

The usual answer is to move to a smaller manufacturing process in the chip fabrication plants, which makes each of the millions of transistors inside the CPU smaller. This has all sorts of benefits and results in smaller, cheaper processors that can operate faster while using less power.

This approach has worked well over the years, and while there are always technical hurdles to overcome, along with huge investments to be made in fabrication equipment, the benefits are almost inevitable. Unfortunately Intel hit a series of major problems when it moved its Pentium 4 from the 0.13-micron Northwood core to the 0.09-micron (90nm) Prescott, which meant that it was unable to increase the core speed of the processor to the 4GHz and beyond that it had been aiming for.

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To make up for the lack of raw clock speed it increased the size of the L2 cache, which in turn raised the transistor count from 55 million to 125 million, and the result of these changes was that Prescott drew up to 103W of electrical power compared to the 89W of Northwood. This was exactly the opposite of what Intel had hoped to achieve with Prescott so it dramatically shifted the direction of its processor development, and the result is the dual core processors that it announced on 4th of April.

In essence the new processors are two Prescotts sat side-by-side on a single processor socket, which means that both cores can run relatively slowly and still provide more computing power than the current Pentium 4. The result is that the transistor count has taken yet another leap to 230 million, while the maximum power requirement is 130W. However, this is a short term measure until Intel is able to complete its development of a true dual cored processor on a 65nm process which will take another year.

The new dual cored processor sees the end of the Pentium 4 name, and it will come in two forms. The Pentium Extreme Edition has Hyper-Threading enabled and the model 840 will debut at a clock speed of 3.2GHz on an 800MHz FSB. While pricing hasn't been confirmed we expect Intel to price it at the usual Extreme Edition level of US$999, which makes it technically interesting but realistically no-one is going to buy it at that price.

The mainstream dual core processor is Pentium D which will have Hyper-Threading disabled and will launch at speeds of 2.8GHz-3.2GHz. On the face of it this is a step backwards as Pentium D will have two true cores, compared to two virtual cores in the Pentium 4 5xx and 6xx series. In addition the clock speed is significantly lower than Pentium 4 which you can readily buy at 3.6GHz, and in straight benchmark tests Pentium Extreme Edition and Pentium D return results that are proportional to their raw clock speeds, but when you try multi-tasking you'll find that there's more to the story.

Most of us don't multi-task in the true sense. We may have a browser open at the same time as a photo editor and word processor but we tend to do one job at a time. You can see the result when your PC starts a virus scan as this will generally take all of the free resources and lock your PC solid for a few minutes, so we have learnt to do one thing at a time.

With Pentium Extreme Edition we started a full virus scan running and at the same time we set iTunes to encoding a few albums of MP3 files, and then we started to play Doom 3 with the two jobs running in the background. Most PCs would have refused to start the game running but with Pentium Extreme Edition we were unable to detect any slow-down at all and the game was completely smooth.

Even though the new dual core processors use the same LGA775 socket as Pentium 4 Prescott, you won't be able to perform a straight upgrade as the processors require support from the motherboard chipset. Intel has launched the 945 and 955X chipsets which share features with 915 and 925X, except that they support the new processors, and we understand that Nvidia's Nforce for Pentium 4 also supports dual core processors.

AMD coined the phrase 'A new kind of fast' for its Opteron server processors, so we're going to borrow the tag and stick it on Intel's new dual cored Pentium processors. They really are that good, and we are sure they will prove to be a revelation to desktop PC users in the next year or two.