Right now, there are five different chipsets for Athlon 64 family processors: AMD-8000, ALi 1687, NVIDIA nForce3 150, SiS755 and VIA K8T800. However, when it comes to real life, we can see only two chipsets being really used in mainboards: the one from NVIDIA and VIA Technologies. AMD’s chipset is too expensive and also requires a six-layer PCB design. Thus, it is only used for server solutions. The chipsets from ALi and SiS haven’t yet started shipping. So, we actually have only two Athlon 64 chipsets now.
The following table lists their main characteristics:
NVIDIA nForce3 150
Bus connecting to the South Bridge
V-Link 8x (533MB/s)
2 ports supporting RAID 0 and 1
As we’ve already said, the Athlon 64 architecture puts the memory controller into the central processor. It means the chipset has nothing to do with the supported memory types. Any Socket754 mainboard, whatever chipset it is based on, potentially supports single-channel DDR200/266/333/400 SDRAM. The maximum amount of memory is six banks with DDR333 or slower and four banks with DDR400. To cap this all, the CPU-integrated memory controller supports ECC.
Let’s now examine the chipsets in more detail. The VIA K8T800 does offer wider opportunities as far as peripheral devices connection concerns than the NVIDIA nForce3 150. Particularly, the South Bridge of VIA’s chipset supports the Serial ATA interface. The nForce3 has one big advantage, though. This is a single chip chipset, thus allowing simpler and cheaper mainboard designs. Moreover, the next version, nForce3 250, is going to emerge early next year. It is going to be a full-fledged product supporting Serial ATA and eight USB 2.0 ports as well as a Gigabyte Ethernet controller. The current version, nForce3 150, often comes complemented by an external onboard Serial ATA controller.
Again, since the memory controller is built into the Athlon 64 CPU, mainboards based on different chipsets won’t differ greatly in performance. The crucial criteria for any mainboard are now its functionality and the IDE controllers implementation. As for the AGP 8x bus, it is doubtfully a bottleneck in today’s systems: the quality of its implementation doesn’t affect the performance that much in a majority of tasks.
Among the peculiarities of the Socket754 chipsets, I’d like to single out the HyperTransport bus that connects the chipset to the processor. This bus can work at different speeds. The maximum throughput is achieved by clocking the HyperTransport at 800MHz. Note that the NVIDIA nForce3 150 uses the HyperTransport bus in a slower mode than the VIA K8T800 does. In theory, this may slow down the performance, although slightly. HyperTransport in nForce3 150-based systems works at 600MHz frequency (unlike the maximum 800MHz), which appears quite enough to satiate the needs of the peripherals and the graphics subsystem, which has its own dedicated graphics memory and rarely calls for the system memory through the CPU. However slight, the difference between the frequencies does show up in some tasks. You will see it in the tests later today.
Now, let’s take a closer look at the products the manufacturers offered for our tests.