Performance on the QX6700 is pretty good in most modern applications. Sysmark 2004 shows performance was near that of the X6800 and above that of the E6700 from previous Intel CPUs. Doom 3 is a multi-threaded game app, and it shows a increase in performance vis-à-vis the X6800 in the game.  The QX6700 outperforms the competition by quite a margin (AMD CPUs), but the Core 2 Duo E6700 and Core 2 Extreme X6800 come close due to the lack of quad CPU support in the applications.

System tests

Game tests

Memory tests

3dmark

SpecViewPerf