Memory subsystem performance

This test gives us a visual representation of the cache and memory subsystems of these CPUs. I've limited the results to the five new processors we're testing, plus one more for comparison. As you can see, the higher-end CPUs tend to have larger, faster caches, as one would expect. The performance of the L2 and L3 caches of the Core i7-975 is truly remarkable. Meanwhile, the only real difference between the Core 2 Quad Q8400 and Q9400 is illustrated at the 4MB block size, where the Q9400's larger L2 caches come into play.

Since it's difficult to see the results once we get into main memory, let's take a closer look at the 256MB block:

The Core 2 processors' throughput is generally limited by their front-side bus speeds, while the AMD processors and the Core i7s have no such bottleneck.

The front-side bus also adds a latency penalty to memory accesses, which is why the Core 2 processors and the Pentium E6300 cluster near the bottom of these results. Interestingly, with no L3 cache onboard, the Athlon II X2 250 is a little quicker getting out to memory than the Phenom IIs. Again, though, the Core i7 is just an absolute monster, with the fastest memory subsystem by far in every way we've measured.