SiS’ R659 chipset that has not succeeded in getting to the market will not be the last desktop chipset with RDRAM memory support. Apparently, there are more core-logic products coming out from Silicon Integrated Systems with support faster flavours of RDRAM later this year.
A chipset that has never seen the light of the day – SiS R659 – is the world’s first core-logic with quad-channel RDRAM PC1200 memory controller offering up to 9.60GB/s of peak memory bandwidth. Due to the lack of actual advantages the R659 can bring over competing solutions, such as SiS’ own 655FX or Intel’s i875P, no mainboard makers except ASUSTeK expressed interest in the chipset. The latter has not delivered its R659-based offering as well, indicating that the current RDRAM implementation is not something the industry needs. However, looks like SiS thinks differently.
A report at AnandTech claims there are SiS R659FX and SiS R659TX coming out in the Q3 2004 and Q1 2005 respectively. Both parts sport 400, 533 and 800MHz processor system bus, PCI Express x16 interface for graphics cards as well as quad-channel RDRAM memory controllers. The difference between the two chipsets will be the maximum speed of memory the core-logic can handle. The “FX” is designed to work with PC1333 RDRAM, the “TX” is intended for PC1600 RDRAM.
Prospects of RDRAM-based PC memory sub-systems are not pretty clear these days. Taking into account that AMD integrates memory controller inside its AMD64 processors, there is only one platform that remains for Rambus memory – Intel NetBurst. Processor system buses of modern Intel Pentium 4 CPUs are capable of pumping up to 6.40GB data per second. Quad-channel RDRAM memory can theoretically provide us 9.60GB/s, 10.66GB/s or 12.80GB/s throughput when using 1200MHz, 1333MHz or 1600MHz memory chips. Obviously, such memory bandwidth is not something desktop Pentium 4 systems really need. And keeping in mind the cost of RDRAM as well as scalability of DDR-II, it is hardly possible that desktop platforms will ever use Rambus memory again. It is more likely that at some point RDRAM will find itself in Xeon-based servers powered by non-Intel chipsets, though, it is not something the market generally expects.
Hsinchu, Taiwan-based Silicon Integrated Systems understands that RDRAM has pretty uncertain future quite clearly, therefore, the main hero of SiS’ Pentium 4 chipsets in 2004 will be SiS656 that comes this April as well as its improved version called SiS656FX slated for the fourth quarter release. Both parts will feature 400, 533 and 800MHz Quad Pumped Bus, PCI Express x16 port for graphics cards as well as dual-channel memory controllers. The difference will be in supported memory: the “FX” version will be DDR-II core-logic only sporting 400MHz, 533MHz, 667MHz and even 800MHz DDR-II with or without ECC, while the original SiS656 will be a lot more conservative – it will sport traditional dual-channel PC2100, PC2700 and PC3200 DDR as well as 400MHz, 533MHz and 667MHz DDR-II SDRAM.
In addition to already announced SiS755FX for AMD Athlon 64 and AMD Opteron processors, SiS will unveil its SiS756 core-logic with 1GHz HT bus, PCI Express graphics and PCI Express x16 interfaces in May 2003.
The most advanced I/O controller from SiS in the 1H 2004 will be the SiS965L that boasts 2 PCI-Express x1 ports, 6 PCI ports, 8 USB 2.0 ports, 8-channel sound, 10/100Mb/s Ethernet, 2 Serial ATA-150 ports with hot plug functionality and RAID, 2-channel Parallel ATA-33/66/100/133 and so on.
The information is not official and SiS’ representatives would not comment on the story.