Memory performance

Although the dual-channel DDR2-800 memory subsystems on our Intel 975X test rigs have a peak theoretical memory bandwidth of 12.8GB/s, the Extreme Edition 965's system bus maxes out in theory at 8.5GB/s. In actual use, with overhead, our synthetic memory bandwidth tests place this combo at about 6.6GB/s—below its theoretical peak but above anything else around. The dual-core Extreme Edition 965 achieves only a hair's breadth more throughput than the single-core P4 Extreme Edition 3.73GHz

Our rendition of Linpack is no great measure of scientific computational power, but it does give the Extreme Edition 965 a chance to show off its boffo L2 cache, which markedly outperforms the 90nm Pentium 4 XE 3.73GHz's like-sized cache. Intel's 65nm SRAM offers superior performance at the same clock rate.

The 965's impressive memory bandwidth and large, speedy L2 cache can help mask memory access latencies, but those latencies remain quite a bit longer than on Athlon 64 processors with their built-in, on-chip memory controllers. Note, also, that the Extreme Edition 965's faster front-side bus doesn't really help cut access latencies in comparison to the Pentium systems with an 800MHz bus.