Intel Core 2 Extreme Review Selma AL

This section of the Labs test is the only one not to see any new models launched or old models discontinued since last year's CPU megatest.

However, while Core 2 Extreme CPUs have in theory been superseded by the Core i7-series, they remain some of the fastest processors available.

The QX9650 was the world's first 45nm CPU and also marked the introduction of the Penryn architecture. This yielded an average 10 per cent extra performance over earlier Core 2 Extreme CPUs, and was later rolled out to the Core 2 Duo and Quad series.

Both the QX9650 and QX9770 have four cores and the same cache arrangement of 6MB of Level 2 cache shared between each pair of cores. While the QX9650 is clocked at 3GHz and has a 1,333MHz effective FSB, the QX9770 runs at 3.2GHz and has a 1,600MHz-effective FSB. As both models have an unlocked CPU multiplier, they're very easy to overclock.

Despite its premium pricing, the QX9650 is matched in performance by the £643-cheaper Q9650, which runs at the same frequency. However, the QX9650's video encoding score of 1,799 and high frame rates in games are among the highest of any CPU. The QX9770 is only slightly faster, but it's still the fastest LGA775 CPU you can buy.

By increasing its vcore to 1.55V, we could overclock the QX9650 from 3GHz to 3.83GHz, which is a modest improvement, although it's easily beaten by the Q9650, which overclocked to 3.96GHz. As always with overclocking, your mileage may vary, but it isn't uncommon for Q9650s to overclock further than QX9650s, as they're based on a later stepping. In contrast, with its vcore increased to 1.48V, the QX9770 would happily benchmark at 4.2GHz - the highest frequency at which any quad-core LGA775 would stably run. While the benchmark results at this frequency are very fast, the much cheaper Core i7-940 is faster.

If you already own a Core 2 Extreme then it's worth holding on to it, as both models produce very competitive performance. However, neither model is currently worth buying, as a Core i7 is much faster and cheaper, even when you take into account the high price of LGA1366 motherboards and triple-channel DDR3.

Author: James Gorbold & Antony Leather

Intel Core 2 Extreme