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SiS 655FX Chipset Reference Motherboard

SiS 655FX Chipset Reference Motherboard - PCSTATS
Abstract: With the SiS655FX, the company is now positioned to be a key player in the Intel chipset market, offering better value to motherboard makers.
 94% Rating:   
Filed under: Motherboards Published:  Author: 
External Mfg. Website: SIS Nov 03 2003   Colin Sun  
Home > Reviews > Motherboards > SIS 655FX

What is HyperStreaming?

When it comes to multitasking, SiS has implemented a technology called Multiple Streams with Pipelining and Concurrent Execution. What that describes is a split transaction technique for the 655FX chipset - basically they split transactions into two independent sub-transactions, one a request, and the other a response transaction. When other transactions can use the free EU's in between, they do, thus increasing overall efficiency.

The example above is intended to illustrate that four independent request/respond transactions can be computed while a conventional system would only be able to finish two.

To help keep things moving at a quick pace, the SIS 655FX places six request/response channels (three for each channel) between itself and the SIS 964 Southbridge. That is a total of 1.2GB/s of bandwidth between the two core logic chipsets. With traditional chipsets, there are just two channels (one upstream and one downstream), so all data, no matter how trivial, is treated equally and passed through with the same priority.

With HyperStreaming, not only is the data being computed in parallel, certain data streams receive higher priority, and are thus worked on first and have more channels between the bridges. For instance, HDD performance of the SiS964 is among the highest PCstats has ever seen thanks to the fact that hard drive streams have their own independent channels to the Northbridge.

As with life, not all computer transactions are created equal. SiS is a bit vague describing Specific Stream with Prioritized Channel, but it seems with the HyperStreaming, the data that is most critical to the system will be computed first while less essential data will have to wait. For instance SiS claims that HyperStreaming will give access higher access to high bandwidth, low latency programs such as video/audio (which can suffer sync problems) and internet accesses. All priority transactions are tagged with an isochronous bit and then get to pass through the isochronous channel while the rest of the non essential transactions like keyboard strokes, printer commands and mouse movements run through the non isochronous channel.

Think of it as an express highway with its own exit points. The express data doesn't run any faster than the collectors (non iso), but as it's less congested, the pieces of data end up getting to their final destination faster. When HyperStreaming begins to work with another architecture based on different protocols, efficiency and transition between the two becomes very important in order to avoid redundancy. The first part of Smart Stream is Intelligent Arbitration. This feature prioritizes streams according to their data types and readies the data to be sent.

Non-post and response request are higher up on the food chain than Post requests because non-post and response requests use more aggressive insurances and directly reduce the wait state of the processor and other devices. Smart Stream allows for a higher cache hit rate and if that fails system memory hit rate is also much higher. HyperStreaming allows for two levels of intelligent arbitration to schedule commands and data, and improves bus utilization and efficiency.

Smart Flow Control is used to improve transfer rates between the processor and chipsets/devices. With HyperStreaming, no matter how complex the commands are they only use one cache line. If you'd like to learn a bit more on SiS's HyperStreaming please check out SiS' informative little flash movie. Now let's take a look at how the SiS 655FX chipset performs against the competition.

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Contents of Article: SIS 655FX
 Pg 1.  SiS 655FX Chipset Reference Motherboard
 Pg 2.  A Look Around a Reference Board
 Pg 3.  A unique layout of components
 Pg 4.  SiS 655FX Northbridge
 Pg 5.  — What is HyperStreaming?
 Pg 6.  System Specs and Benchmarks
 Pg 7.  Benchmarks: Winstone 2000, Winbench 99
 Pg 8.  Benchmarks: SiSoft Sandra 2003, SpecviewPerf 7
 Pg 9.  Benchmarks: PCMark2002, 3DMark2001SE
 Pg 10.  Benchmarks: Quake III Arena, UT2003
 Pg 11.  Competition for the i875P and i865PE

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   08 / 18 / 2019 | 2:42AM
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