Socket 939 Chipsets: Motherboard Performance & PCI/AGP Locks

Socket 939: Chipsets and Motherboards

Ever since the introduction of the Athlon 64 on-chip memory controller, computer users have seemed confused about chipsets for Athlon 64. That's understandable, given a market where computer users anxiously await each new chipset to see how it might perform. Chipsets, and the motherboards based on them, varied quite a lot in performance, and how a chipset performed compared to others was life and death in the market.

Athlon 64 has changed the end-all importance of chipsets, at least for Athlon 64, just by moving the memory controller from the chipset to the processor. This means that the same VIA K8T800 PRO or nVidia nForce3-250 can be used in a single-channel Socket 754 board, or a Socket 940 Dual-Channel Server board, or a new Socket 939 dual-channel motherboard. All three of these boards use the same core and differ only in the memory controller - which is a part of the CPU.

This is an important distinction, because there really are not any new chipsets that were introduced for Socket 939. The new chipsets were introduced one to two months ago, in other sockets, as we showed you in those chipset launches. The new boards are using either the nVidia nForce3-250 that we reviewed in-depth in our 2-part March review: nForce3-250 - Part 1: Taking Athlon 64 to the Next Level and nForce3-250 - Part 2: Taking Athlon 64 to the Next Level; or they use the VIA K8T800 PRO chipset, which we covered in our May review, VIA K8T800 PRO: PCI/AGP Lock and 1000 HyperTransport for Athlon 64. Chipset and motherboard makers can and have confused computer users by using different names for different features of the chips used for Socket 939, but under the hood, the chipset requirements are the same for Athlon 64, whether the chipset drives Socket 754, Socket 940, or Socket 939. What makes these sockets different is the memory controller that sits on the CPU - not the different socket.

SiS has also announced an upgrade to their 755 chipset that supports 1000 Hyper Transport called the 755FX, and they are also displaying a new Athlon 64 chipset version called 756 for PCI Express and 1000 HT, but at launch, only boards from VIA and nVidia were available. We plan to look at the other new chipsets for Athlon 64 as soon as they become available.

The important thing to remember is that Socket 939 does have a new specification of a 1000 MHz Hyper Transport speed. This can be used for all chipsets, as VIA has chosen to do for the K8T800 PRO chipset, or there can be different versions with different Hyper Transport Speeds as nVidia has chosen to do with the nForce3-250/Gb (800MHzHT) and nForce3-250 Ultra (1000MHz HT). This only means manufacturers can speed-grade the chipset or separate different versions with different features, but the same nForce2-250Gb Ultra chipset can really drive any of the Athlon 64 sockets.