Intel's next generation CPU, codenamed Penryn, has finally hit the PC World test labs, and there are a few new things to get excited about. Probably the most touted feature of this new Core 2 CPU is that it has been built using Intel's new 45-nanometre (nm) transistor technology. However, it's not all about the size. It's also about what they're made of.

We took a look at Intel's QX9650 Core 2 Quad CPU. Like the QX6850 we tested recently, the new QX9650 has a 1333MHz front side bus (FSB) and a core speed of 3GHz, but we can expect Penryn CPUs to launch up to 1600MHz FSB speeds with even faster cores. The QX9650 also uses a 12MB L2 cache (2x 6MB caches) as opposed to the maximum 8MB L2 cache (2x 4MB caches) on Conroe processors.

As we've already mentioned, the most touted feature of this CPU is its 45nm transistor technology. Transistors are tiny gates that exist in either an on or off state and are the physical representation of a computer's 1's and 0's. The previous generation of CPUs codenamed Conroe, were built using a 65nm manufacturing process, but Intel's new 45nm transistors allow approximately twice the density of transistors on a single chip.

According to Intel you could fit approximately 2000 45nm transistors across the width of a human hair and they can switch on and off approximately 300 billion times per second. However, as transistor technology gets ever smaller, the instance of power leakage becomes more prevalent. Maintaining control of the on and off states gets increasingly difficult until it's less of a design flaw, and more of a flaw in the materials being used.

The transition from 65nm to 45nm has been made possible by the new hafnium-based High-K gate dielectric and a new metal gate electrode, rather than a polysilicon gate that's been in place since the late 1960s. The new materials allow, in a sense, for the on state to be more on, and the off state to be more off. What this all boils down to is two main points; a performance increase from the transistor, and reduced power leakage, a problem that plagues device reliability and the power-per-watt efficiency.

The next step forward that Penryn offers is a move to the new Intel SSE4 instruction set. SSE4 will bring 54 new instructions that act like a language between the capabilities of the new CPU and software that has been written to take advantage of it. Most of the benefits fall under media encoding, 3D applications (such as games and model rendering) and data mining. Put simply, SSE4 reduces the number of steps that need to be taken to complete an operation, theoretically increasing performance. At this stage there is only one application available with SSE4 optimisations, and that's DivX 6.6.1.

We ran a range of tests from video and audio encoding to gaming and rendering tests, but the most telling test was our own WorldBench 6 benchmark, which runs the computer through a series of common applications and workload environments to gauge its ability. As you can see from the benchmark results, less taxing applications like Firefox and Microsoft Office gained little, while 3DS Max DirectX and rendering tests benefited and the Windows Media Encoder 9 results also showed improvement. We also saw notable gains in the WinZip compression test, in our Cdex MP3 compression test and in the Half-Life 2 gaming test. None of these applications use SSE4, but are clearly improving from the new CPU (see graph for details). The total score of 130 in WorldBench 6 puts it on par with the QX6850 when it is overclocked to 3.6GHz, and when overclocked the Penryn QX9650 reached a massive 140.