AMD vs. Intel: 64-bit Windows Dual-Core Shootout

Part II: Gunfight at the 64-Bit Corral
When it looked like AMD was going to render Intel's multibillion dollar IA64 effort (aka Itanium) irrelevant with its brassy push into 64-bit computing using an extended x86 architecture, Intel responded with EM64T. When it was first revealed that Intel had an x86-64 project in the works, codenamed Yamhill, the company at first denied the project's existence. Eventually, though, EM64T surfaced, and it proved to be a near-clone of AMD's x86-64. There are some subtle differences in calling conventions between the two processors, but the differences are slight enough that compatibility isn't usually a worry.

Last week in Part I, we took a look at the AMD dual-core Athlon 64 X2 4800's performance on 64-bit Windows. As it turned out, Windows XP Pro X64 ran most 32-bit applications just fine on the X2 4800, and 64-bit code showed a few modest performance gains.

Our article generated considerable interest in the community at large. We received several interesting emails on the topic. One of the most salient was from Joe Landman of Scalable Informatics. Scalable ran a variety of 32-bit-vs-64-bit tests on Opteron CPUs. Although somewhat synthetic, the tasks run were applicable to certain types of scientific computing. SI found that 64-bit code was almost always faster than 32-bit code, when properly written.

David Wren of Passmark Software, an Australian utility software company, echoed those findings, and allowed us to use Passmark's Performance Test, which is available in both 32-bit and 64-bit versions. PPT is synthetic in nature, but can yield interesting results that point to potential theoretical gains with 64-bit code.

Given Intel's renewed focus on both 64-bit x86, coupled with its rapid, if somewhat improvisational, push into dual-core processing, we wanted to see just how well Intel's dual-core processors fared with 64-bit Windows relative to AMD's best. So we loaded up a system with an Intel Pentium Extreme Edition 840 and took it for a spin. Intel is nothing if not a fierce competitor, so let's see how the dust settles. Continued...