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SiS655 Heralds Dual-Channel Era

Tags: SiS (TPE:2363)

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[Taipei, Taiwan. April 23, 2003] The SiS655 chipset from Silicon Integrated Systems (SiS) arrived just as the major motherboard companies were exploring the huge potential for dual-channel DDR products. Due to the right timing and specifications, the company’s first dual-channel memory controller is set to become its high-end flagship. Major motherboard manufacturers including Aopen, Asustek, Gigabyte, Iwill and Micro-Star International (MSI) have been impressed with the chipset’s performance, in particular the bandwidth it delivers and a host of new motherboards have already adopted it and been launched globally. Power users and game aficionados, who recognized the solution’s excellent price-performance ratio, have also responded favorably and as dual-channel demand takes off the chipset’s position in the market is ensured.

Some model numbers will differ between territories, however the best-known motherboards using the SiS655 include the Aopen AX45-4D Max, Asus P4SDX, Gigabyte GA-SINXP1394 (GA-8SQ800 Ultra2), Iwill P4DR and MSI 655Max. Each of these targets specific market segments, with specifications and add-on features varying according to the needs of the users and the manufacturer’s pricing strategy.

Aopen’s AX45-4D Max complements the SiS655 and the SiS963 media I/O controller, provides on-board IEEE1394 connectivity. 10/100 Ethernet is provided by Realtek’s 8100BL and the Realtek ALC650E provides 6-channel audio. Aopen includes effective backup, recovery and debugging solutions including the companies own DieHard BIOS, EzRestore and Dr Voice II.

The Asus P4SDX adopts the SiS963L media I/O controller that, in addition to standard I/O functionality, offers 10/100 Ethernet and an S/PDIF (RCA) optical interface. Asustek’s proprietary “instant music” function allows users to play audio CDs without needing to boot their system and the “CrashFree2 BIOS” feature offers unmatched security and reliability. The motherboard also comes with a 5.25-inch “J-panel” that can be installed to bring the USB 2.0, S/PDIF out, microphone-in and line-out connectors to the front of a PC.

Gigabyte’s GA-SINXP1394 stands out when placed with other SiS655-based motherboards. The highlighting of different connectors with a variety of colors leaves a vivid impression. The motherboard comes with three daughter boards: a DPS (dual power system) module, an IEEE1394 extension and a Serial ATA expansion card. Gigabit Ethernet and dual RAID support top off the long list of features. With so many “duals” – dual power, dual logical processors, dual channel, dual RAID, dual BIOS and dual cooling – Gigabyte has coined the phrase “The 6-Dual Miracle” to promote this product. On Gigabyte’s website, users can find three SiS655 motherboards: the GA-8SQ800, GA-8SQ800 Ultra and this board, the GA-SINXP1394.

Iwill has launched the P4DR-SATA with serial ATA and IEEE1394 support implemented alongside the standard SiS655 features (a board without these additional I/O options implemented is also available). Overclocking is available through Iwill’s MicroStepping technology and the board offers on-board, six-channel audio via Realtek’s ALC650.

The MSI 655Max completes this list of leading-edge boards. The 655Max series offers three models: the 655MAX-L, 655MAX-LS and 655MAX-FISR. The 655MAX-LS offers 10/100 Ethernet and serial ATA interface I/O, while the top ranking 655MAX-FISR offers gigabit Ethernet, serial ATA RAID and IEEE1394.

Aopen AX45-4D Max
Asus P4SDX

Gigabyte SINXP1394
Iwill P4DR

MSI 655Max
SiS655 reference board


In terms of layout, except for the Gigabyte SINXP1394, the major SiS655 motherboards all follow the reference design for the position of the two memory slots, with the two slot-pairs located at 90-degrees to each other. The Gigabyte board uses colors to differentiate the slots, not position.

All boards using the SiS655 now support Intel’s Hyper-Threading technology and offer the performance benefits that come with it. The SiS655 also provides:

n 533MHz FSB Intel Pentium 4 processor and Hyper-Threading support.

n AGP 8x graphics interface support.

n Dual-channel, DDR333 memory controller and SiS MuTIOL® 1G technology to link the SiS655 to the SiS963 south bridge. This controller can operate at either a 1x128-bit or 2x64-bit mode. It can boost memory bandwidth up to 5.4GB/s to support the characteristics of different DIMM devices with plenty of headroom for dual-channel performance and other functions, such as 8x AGP support. Working together with the SiS963 south bridge, the SiS655 provides support for high-speed IEEE1394, USB 2.0 and two ATA 133/100/66 IDE connectors.

The SiS655 is at the leading edge of today’s dual-channel DDR market but it is not alone. New releases of related products will herald a major shift in motherboard technology, with dual-channel DDR technology eventually moving into the mainstream of performance boards. As the market develops, the SiS DDR chipsets – the SiS648 single-channel solution and the SiS655 – with their strong performance and full range of motherboard solutions available at competitive prices, are well positioned as the best value choice for Pentium 4 motherboards.

About Silicon Integrated Systems Corp. (SiS)

Silicon Integrated Systems Corp. (SiS) is a worldwide leader in the development, manufacturing and marketing of leading-edge logic products, including core logic, multimedia, connectivity and information appliance. The company was founded in 1987 in the Hsinchu Science-based Industrial Park in Taiwan and has been listed on the Taiwan Stock Exchange (TSE2363) since August 1997. SiS combines professional chip design with advanced semiconductor manufacturing technologies. For more information, please visit