SiS 655FX Chipset

Intoducing the SiS655FX Chipset
An Overview of Functionality and Performance

By: Jeff Bouton
October 2, 2003

By now you all know the drill, Intel or AMD release a new chipset for their processor platform and the other third party manufacturers, like VIA, NVIDIA, ALi, and SiS, are soon to follow.  This time around we are talking about the latest release from Silicon Integrated Systems, with their SiS655FX chipset.  Their latest incarnation is a potent package, challenging the Intel 865/875 family chipsets in an effort to offer some competition in both price points and features.  SiS introduced several new features to give the SiS655FX an edge over the competition, with the most important being the introduction of HyperStreaming.  By maximizing bus bandwidth between the Northbridge and Southbridge, SiS aims to improve performance by reducing any bottlenecks between the two chips.  This will allow for better communication and should result in an improvement with data transfer, that can be evident in hard drive performance and other IO performance.

Recently we were presented with a reference motherboard from SiS to give us a taste of what the SiS655FX was capable of.  So let's get things started by getting acquainted with what the SiS655FX has to offer, then we'll size it up against an Intel 865PE based motherboard, to see how the latest from SiS stacks up.
 

Features of the SiS 655FX Chipset Features and Functionality

The latest SiS Chipset is a combination of two components, the SiS655FX Northbridge and the SiS964 Southbridge.  The 655FX Northbridge handles all of the CPU and Memory functions as well as AGP processes.  The Northbridge has been updated with a dual DDR400 memory controller, for a maximum bandwidth of 6.4GBs per second.  This kind of bandwidth should be more than sufficient to insure that there is no bottleneck, between the memory access and the Intel's Quad Pumped Processor bus, which is supported up to 800MHz for the most recent Northwood cores.  Each memory slot can support up to 1GB DIMMs, totaling 4GBs. 

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The Southbridge handles all of the peripheral functions, such as providing integrated 10/100 LAN, Dual IDE and SATA channels, and 8 USB 2.0 ports to name a few.  The North and Southbridge are connected Bi-directionally at 533MHz yielding an effective bandwidth of 1GB/s.  Dubbed "HyperStreaming", this higher bandwidth ensures smoother operation of peripheral components as the communication between the North and Southbridge is optimized.  The most obvious improvement in performance should be found with data transfer and hard drive performance.