Socket 939 Chipsets: Motherboard Performance & PCI/AGP Locks

Index

After a very long wait, Socket 939 is here in full force as you read in our review of the Socket 939 processors. We gave you an in-depth dissection of the new FX53 and 3800+ for Socket 939, plus a head-to-head comparison of the performance of the 3 AMD sockets. The purpose of this review is to examine the motherboards and chipsets that are also being introduced for Socket 939. We also used the opportunity of being here at Computex to look more deeply into what we have found, which is a developing problem with the VIA K8T800 PCI/AGP lock feature.

Almost since the introduction of Athlon 64 and Athlon 64 FX, AMD fans have been looking forward - forward toward the introduction of Socket 939. The original AMD enthusiast part, Athlon 64FX, was an excellent performer, but many complained that Socket 940 required expensive dual-channel registered memory instead of the unbuffered DDR that they already owned. Since FX shared Socket 940 with the server-geared Opteron, the price of admission to the AMD Enthusiast A64 was just too steep for most end-users. AMD had also introduced the more mainstream Athlon 64 in Socket 754 that could use cheaper unbuffered memory, but it was a single-channel solution and most wanted to be able to use the dual-channel memory solution that they associated with the top-performing Pentium 4 solutions.

Socket 939 would fix all this, the logic went, with a unified Socket 939 supporting Dual-Channel unbuffered memory as a platform for a full-range of new Athlon 64 processors from entry-level to enthusiast. Basically, this was another argument for the ability to buy a cheaper Athlon 64 for Socket 939 and to have an upgrade path for more capable Athlon 64 processors in the future. This always sounds good, even if the reality is that most enthusiasts upgrade the motherboard more frequently than the CPU. Whichever is upgraded, the idea of a universal CPU socket for Athlon 64 had great appeal, along with the supposed giant performance boost that Dual-Channel memory would bring to Athlon 64. This reasoning was based on the faulty assumption that the Athlon 64 would benefit from greater memory bandwidth in the same way Pentium 4 had, forgetting that Athlon 64 was not a similar "deep-pipes" design that was starved for memory bandwidth.

Even the chipset makers have added to the perception that Socket 939 would be "the one" from AMD. Both major Athlon 64 chipset makers introduced updated versions of their chipsets in the last two months to be ready for the 939 push. Both chipsets featured 1000 HyperTransport. nVidia did a massive upgrade of the feature set and fixed problems with their first generation PCI/AGP lock. VIA added their first PCI/AGP lock for asynchronous operation in response to the vocal complaints from the Enthusiast market. We have already examined these new chipsets in detail in our launch reviews for each chipset, but now that 939 is finally here, we are finally seeing enough boards with the new VIA K8T800 PRO and nForce3-250 Ultra to take a closer look at how some of these new features work - or rather, don't work in some cases.