Labs

To see the results table, click here.

To see the benchmarks, click here.

Intel's Core 2 Quad processors have four cores, which makes them ideal if you want to run many applications simultaneously. Alternatively, by using multi-threaded applications, such as our Video test, you can put all four cores to work on a single task. This gives impressive results, reducing the processing time to a fraction of what was possible with a single core processor.

A Core 2 Quad processor is basically two Core 2 Duo processors stuck together. Each half has its own L2 cache, which is shared by both cores. However there's no unifying L3 cache, as found on AMD's Phenom processors, so data may have to be duplicated across both caches.

Different ranges

The 6000 series of processors

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have a Kentsfield core and were Intel's first desktop quad-core processors. They are manufactured using a 65nm process and have an external bus speed of 1,066MHz, just like many of the 6000-series Core 2 Duos. Each pair of cores has a 4,096KB shared L2 cache, just like each processor core in the 6000-series Core 2 Duos.

The newer 9000 series of processors uses a Yorkfield core, which is manufactured using a smaller 45nm process. This makes it more power efficient and cooler in operation. They have a quicker 1,333MHz external bus speed, too. Most have a pair of massive 6,144KB L2 caches - the biggest we've ever seen - but Intel's latest Core 2 Quad processor, the Q9300, has only half this amount, sharing 3,072KB between each pair of cores.

Specific processors

The Core 2 Extreme QX9650 is the fastest Core 2 Quad processor on paper, and was also the fastest chip in our benchmarks. Its Extreme branding means that the multiplier is unlocked, making it more flexible for overclockers, who will want to push it faster still. However, at £642 inc VAT it's simply too expensive for most.

Compared with its Extreme sibling, the Q9550 is more reasonably priced at £370 including VAT. However the Q9450 is almost as fast and costs just £204 including VAT. If you're looking for a quad-core processor, this is the one we recommend. The Q9300 is expensive at present given its smaller cache size. It's very new, though, and prices can fall quickly, so it's worth checking the latest prices before ruling it out.