Intel - Core 2 Extreme QX6700 review

Intel is on a roll after the launch of Core 2 Duo E6700 in July 2006 and here we are, a mere four months later, with the launch of the quad core Core 2 Extreme QX6700 which was codename Kentsfield during development.

No doubt when Intel releases non-Extreme versions of this processor they will be called Core 2 Quadro or Quattro or something to reflect the four cores, provided it can find a name that hasn't been snapped up by Nvidia for professional graphics cards or Audi for four wheel drive cars.

In essence Intel has shoehorned a pair of Core 2 Duo processors on to a single LGA775 die, so the quad core runs on the same 1,066MHz Front Side Bus as Core 2 Duo and is fabricated on a 65nm process. There is 4MB of L2 cache for each pair of cores, so that's a total of 8MB of cache, and the core speed is similar to Core 2 Duo.

Core 2 Duo E6700 runs at 2.66GHz and has a TDP (Thermal Design Power) of 65W while the Core 2 Duo Extreme X6800 runs at 2.963GHz and has a TDP of 75W. By contrast the quad core Core 2 Extreme QX6700 runs at 2.66GHz and has a TDP of 130W so it truly is a pair of E6700 CPUs in a single processor socket. Let's not lose sight of the fact that the final versions of dual core Pentium 4 had a similar heat profile, so the technology to keep the processor cool is well established.

The Intel Press kit consisted of a QX6700 processor, a heatsink and a D975XBX2 motherboard with a Beta BIOS. Although the 975X chipset supports both Core 2 Duo and Kentsfield, it isn't necessarily the case that every 975X motherboard will support Kentsfield, so you need to check that your motherboard is 'validated for quad core'.

We understand that the differences between a 'good' motherboard and a 'bad' one come down to power regulation hardware. We laid the D975XBX2 next to a D975XBX and were unable to see any differences, but were told that the new board supports DDR2-800 memory and has enhanced audio control. Once we'd finished testing we played mix and match by plugging the quad core into the old D975XBX and it performed perfectly.

The move from a single core processor to dual core was like the difference between night and day, as you suddenly find that burning a CD or encoding MP3s doesn't make your whole PC freeze solid.

The move to quad core is far less dramatic as there is a limit to the number of applications that you can run simultaneously, but even so there's Windows in the background, your e-mail agent, anti-virus, anti-spyware, the music you're playing, your Internet browser, Word and Excel. By contrast an intensive 3D game is unlikely to use all of the abilities of the processor as very few games are threaded for multi-processor hardware.

We ran POV-Ray rendering benchmark on the Core 2 Extreme QX6700 as the 3.7 Beta has the facility to run on a single core or on all available cores. On a single core the test took 10 minutes 4 seconds, which is fairly swift, but when we switched to all four cores the test flashed past in 2 minutes 29 seconds.

Clearly the quad core hardware works, and when we ran PCMark05 back-to-back with the Core 2 Duo E6700 (same clock speed, half the cores) we found that the quad core got 8,150 marks and the dual core scored 6,879 marks overall, while the CPU elements of the test also favoured the quad core at 8,433 marks compared to 6,715 marks.

To our mind that accurately reflects the fact that most of us have no need for a quad core processor most of the time, but when you start to make your PC work for its living the extra cores pay dividends.
Intel - Core 2 Extreme QX6700 features - Verdict

In a few years' time we'll be amazed that there was an era when people had to make do with fewer than eight processor cores. The Intel Core 2 Extreme QX6700 is a significant step along the way to processing Nirvana and, although it costs a small fortune, we're very happy that its time has come.