Product Reviews

Intel's Core 2 range of processors impressed us. The E6700 won our Best Component award in Shopper December 2006. Never a company to rest on its laurels, Intel has released the Core 2 Extreme QX6700 processor, which has four processor cores.

From the outside, the QX6700 looks like any other LGA775 processor. While it's pin-compatible with all LGA775 processor sockets, you can't use it with all motherboards. The QX6700 has different power requirements to dual-core Core 2 processors, so check your motherboard manufacturer's website for compatibility information before you buy. Rather than a brand-new processor designed to be quad-core from the ground up, the QX6700 is a bit of a cheat: it is two Core 2 E6700 processors put together in the same package. As with the E6700, the QX6700 runs at 2.66GHz and has a 1,066MHz frontside bus (FSB).

While the processor's specification lists the QX6700 has having 8MB of L2 cache, each pair of cores has only 4MB of L2 cache, just as on a standard Core 2 processor. The cache uses Intel's Smartcache technology, though, adjusting each core's share based on usage. Doubling the number of cores on a chip doesn't necessarily double performance. The FSB speed for the QX6700 is still 1,066MHz, which has to be shared between four cores; with a dual-core processor, each core gets half the FSB bandwidth. Also, placing two Core 2 processors on the same chip increases heat; the QX6700 has a thermal design power (TDP) of 130W - the same as a Pentium D 690 - while the E6700 has a TDP of 65W. Therefore the QX6700 requires a powerful heatsink and fan. It's

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not the ideal processor, then, for building a quiet media PC. The reference cooler we were provided with was very loud at full speed, so we'd recommend buying a quieter cooler for your PC.

Fortunately, you can still overclock easily with the QX6700. As with all the Extreme processors in the Core 2 range, the QX6700 isn't multiplier-locked, so it can be overclocked without having to change the FSB or memory speeds. In practice, this makes it much easier. However, the increased heat output over the Core 2 Extreme X6800 means you'll definitely need better cooling than the reference cooler.

Performance can be tricky to measure with multicore processors, as you need applications that have been written to take advantage of the extra cores. As you can see from our test results, the QX6700 has the highest score we've recorded in our benchmarks, but it is not twice as quick as a Core 2 Extreme X6800. In fact, the multiple-application score isn't quite as high as results we've seen from some PCs with 2GB of RAM, because the Paint Shop Pro test relies more on memory and our test rig was fitted with 1GB of RAM.

When the QX6700 performs a task that gets all four cores cranked up, the results are unbelievable. Our video-editing test returned a score of 484, a clear 157 higher than any other single processor we've seen and almost five times quicker than our single-core reference PC.

We even managed to get a score of 243 in this test while running our Doom 3 test, which managed the same frame rate as when we ran it by itself. So the QX6700 doesn't just let you run two tasks at speed; it also lets you perform two demanding jobs with no obvious drop in its performance.

The QX6700 is very expensive and probably amounts to overkill for most people. Still, if you want the best performance money can buy and wish to run a lot of demanding tasks such as video editing, there is no faster processor and AMD is now well and truly off the pace. Just check your motherboard's compatibility first. For everyone else, the QX6700's release should help push down the price of the existing Core 2 range where the E6700 remains our first choice; see 'Also consider...' below.