AMD's dual-core Opteron processors

MICROPROCESSORS ARE GETTING too hot, requiring too much power, and not delivering enough additional performance for it. That's the basic problem. The engine that's driven the microcomputer's incredible rise in capability over the past 30 years, Moore's Law, isn't quite out of steam yet, but some of its offshoots are on the ropes. CPU designers have nearly exhausted their collective bag of tricks to get more performance out of additional transistors on a chip by increasing parallelism at the instruction level. Speculative execution and deep pipelining are by now very standard features, and CPU designs are getting increasingly complex and hard to manage. When Gordon Moore's goose lays a golden egg and the number of transistors possible on a chip doubles, as it is supposed to do every 18 months, taking advantage of the windfall has proven increasingly difficult.

Fortunately, both AMD and Intel seem to have settled on an answer that should allow them to take advantage of ballooning transistor counts to gain additional performance: thread-level parallelism. By dialing back clock speeds and putting multiple CPU cores on a chip, the theory goes, processor performance can rise as transistor counts do. This sort of parallelism will, of course, be familiar to those who know a thing or two about Opteron processors, which have commonly been employed in pairs as part of server or workstation systems.

We've had a pair of dual-core Opteron processors on the test bench for some time now, and we're pleased to report some rather impressive results. AMD's dual-core design is something more than just a pair of CPUs glued together on a single piece of silicon, and this design choice yields a performance dividend. Keep reading to see how the new Opteron 275 stacks up against its Opteron predecessors and against Intel's latest "Nocona" Xeons. We also have a head-to-head battle of single-socket, dual-core workstation processors: the Opteron 175 versus the Pentium Extreme Edition 840.