Core 2 Extreme QX6700

Previously codenamed Kentsfield, the QX6700 remains in Socket 775 form factor and, with a quick Bios update, can be used with the majority of Core 2 Duo compatible motherboards.

Clocked at 2.66GHz, the same as a Core 2 Duo E6700, the Core 2 Extreme QX6700 is actually two Core 2 Duos fitted together in a single package. As a result, the L2 cache is made up of two 4MB caches, totalling 8MB. As first stated in our news story, Intel will continue to make quad-core processors in this way beyond 2007.

Not being a native quad-core part, this CPU isn’t particularly energy efficient. It has a 130W envelope, which means it dissipates twice as many watts compared to a Core 2 Duo. 130W was typical of the high-end, hot and hungry Pentium D processor.

Users shouldn’t expect a doubling of performance with double the cores. Firstly, the Front Side Bus (FSB), which dictates how fast the CPU can transfer data to Ram and other devices, remains at 1,066MHz. This means the four cores must share and jostle for bandwidth to the Northbridge. Secondly, most day to day software isn’t yet optimized for quad core; a few programs get confused and will not even run when they see four cores.

In our PCmark05 CPU test the QX6700 thrashed out a score of 8,100; the highest score we've ever seen and nine per cent higher than the X6800’s 7,404. In 3Dmark06 CPU test the QX6700 blew everything else away with a score of 3,961, beating the previous top dog, the X6800, by 58 per cent.