First up, we've got a quick snap-shot for you of overall system bandwidth and raw CPU power, with SiSoftware's SANDRA benchmark suite.
Since SANDRA's CPU test modules fully support and exploit the multi-threaded capabilities of both HyperThreading and Dual Core CPUs, the new Pentium EE 840 posts amazing results in this test. Two physical cores clearly are much faster than the two logical cores (with HyperThreading) that are available on the P4 570J. The Athlon 64 4000+ brings up the rear with no multi-threading capabilities at all.
More of the same on the multimedia and SSE side of things, almost 2X the performance.
Here we see a different story that is more representative of the variation in platform configurations we tested. The 955X/Pentium EE 840 system is running DDR2-667 at CAS5 and the rest of the other P4s are running DDR2-533 at CAS3, with the Athlon 64 running DDR-400 CAS2. In the case of the Athlon's dominance in this test, the A64's integrated memory controller offers up superior low latency metrics, while P4 500 series chips also only have one logical CPU competing for system memory bandwidth.