Conclusions
AMD's dual-core Opteron processors are extremely well executed on all fronts, based on what we've seen. AMD's dual-core design has a technical elegance that Intel's can't match, and that design brings superior performance. One Opteron 175 performs slightly better than a pair of Opteron 248s running at the same clock speed, and it does so while consuming less power than a single-core Opteron 152. All in all, very impressive.

Going to a dual-core Opteron does, however, involve some tradeoffs. Fundamentally, one is giving up single-threaded performance in order to gain multithreaded performance. Whether or not this tradeoff makes sense will depend on the kind of applications one plans to run on the system. Many of our benchmarks were multithreaded, but only made use of two threads, leaving the dual Opteron 275 system looking a little pointless. The Opteron 252 system outperformed it in many of these dual-threaded apps, like media encoding. Our other tests, however, showed the Opteron 275s to be an absolute rendering powerhouse. Which processor is the better buy will depend greatly on its intended use.

The rough part of the story is that AMD isn't asking customers to choose between an Opteron 252 and a 275, which could be a tough choice for many workstation users. They've priced the Opteron 265, which runs at only 1.8GHz, right on top of the Opteron 252 at 2.6GHz. That forces one to choose: are you really committed to the idea of dual-core processors or not? For systems that already have two CPU sockets, I'm not sure what I'd choose without knowing the specific types of applications involved. The move to dual-core CPUs effectively ups the ante on thread-level parallelism in workstations, and some classes of applications will benefit from that effect more dramatically, and immediately, than others.

I do think that the answer for single-socket workstations is probably rather straightforward: I'd pick the dual-core Opteron over the single for the same reasons that most workstations have traditionally had multiple processors. Not only will the dual-core CPU bring better multitasking responsiveness, but it will also work well in dual-threaded applications, which are fairly common. In the server space, the choice to opt for dual-core chips for web, database, and terminal severs will also likely be rather easy, given the highly threaded nature of such roles.

There are a number other subplots in our benchmark results, as we discussed earlier, and I won't attempt to address them all here. You've seen the results for yourself. We will probably be sorting through some of the more profound questions about the benefits and limitations of thread-level parallelism for years to come.