Memory performance
We'll begin with our usual set of synthetic memory tests, just to set the stage. The QX6700 doesn't bring any additional memory bandwidth to go along with its additional CPU cores, but we can see what effect its additional bus overhead has on memory access.

All of these synthetic, single-threaded memory tests show the Core 2 Extreme QX6700 performing just like its dual-core sibling, the E6700. Our version of Linpack isn't highly optimized, but it does give us a sense of cache size and performance.

Now for some ridiculously verbose 3D representations of cache and memory latency, just because we can. I've color coded the portions of these graphs to correspond with L1 cache (yellow), L2 cache (amber), and main memory (orange).

Once again, the QX6700 looks very similar to a dual-core Core 2 Extreme. Access latencies are lower on the Athlon 64 thanks to its integrated memory controller, but the Core 2 CPUs look awfully good compared to the Pentium Extreme Edition, likely due to their improved L2 cache prefetchers and their ability to move loads ahead of stores in certain cases, also known as memory disambiguation.