Benchmark results

Memory performance
We'll start out with a page full of useless benchmarks that don't tell us much about the real-world performance of these processors, just because I enjoy it. These memory tests will give you some perspective on how memory subsystems differ between the P4 and Athlon XP, and they will help explain some of the performance differences that will show up in our application benchmarks later on.

Sandra's tests wring out something close to the peak possible memory throughput on most systems.

You can see the three classes of systems here quite clearly. The Pentium 4 systems with RDRAM have the most memory throughput, followed by the DDR333-equipped P4 systems. The Athlon XP rigs are limited to about 2.1GB/s of throughput by their 266MHz front-side bus, despite the fact they have DDR333 memory.

Cachemem measures both read speeds and write speeds, and it's not so aggressive with buffering and SIMD instructions as Sandra.

The RDRAM systems again have the most bandwidth, but notice that the Pentium 4 DDR system is slower than the Athlon XP at writing to memory. That's an unexpected reversal of fortunes. Still, the Pentium 4 systems are much faster exchanging data with memory, overall, than the Athlon XP. The Pentium 4 2.8GHz is especially adept at memory writes with PC1066 RDRAM.

The tables are turned when it comes to memory access latency. The Athlon is out in front here, and the RDRAM-equipped Pentium 4 systems are especially slow. Still, "slow" is a relative term here, and RDRAM's access times are only a little higher than DDR's. Then again, PC1066 RDRAM isn't easy to find, and we haven't even included DDR400 memory in this test. If you'd like to see how DDR400 memory matches up against RDRAM, go here.

Our final memory test is Linpack, which illustrates visually the hierarchy of memory types and speeds from L1 cache through main memory.

At 2.8GHz, the Pentium 4 peaks out just as fast as the Athlon XP, but it does so with larger data sets. The Pentium 4's larger L2 cache and faster front-side bus give it the advantage from about 100K data sets onward.