Memory subsystem performance
Our first few tests are synthetic benchmarks that let us inspect the performance of the cache and memory subsystems.

Sandy Extreme's memory hierarchy achieves more throughput at every step of the way than any other desktop processor. This chip's massive L3 cache gives it a commanding throughput lead at the 16MB block size, where no other desktop CPU comes close. Unfortunately, we suspect few desktop workloads have a working data set large enough to fit into this L3 cache and not into the caches of more pedestrian chips. As a result, Sandy Bridge-E's large last-level cache may be a victim of the law of diminishing returns.

On paper, Sandy Bridge-E has a tremendous amount of memory bandwidth compared to anything else out there. In reality, Sandy Bridge-E has a tremendous amount of memory bandwidth compared to anything else out there, too. What more can you say about this one? With twice the memory channels of its sister, Sandy Bridge, the Extreme part delivers a little more than two times the throughput in our directed test.

I've included this result for completeness, but the outcome is probably a little bit deceiving. I believe the 3960X's 15MB L3 cache is masking some of the access latency at this 16MB block size. Next time out we'll have to sample from a different spot or use another tool to measure latencies to main memory.

For what it's worth, our tool reports Sandy Extreme's L1 cache latency at four cycles, L2 latency at 12 cycles, and L3 latency at 30 cycles.