The SiS 735 chipset

The SiS 735 chipset

Unlike the other DDR chipsets on the market, the SiS 735 chipset is a single-chip solution. Rather than implementing the functions of a North Bridge and South Bridge on two physical chips, SiS has integrated them into one sole chip, 735. What else would you expect from a company that has a long history of providing chipsets with high levels of integration?

Since it only utilizes one chip, motherboard designers can offer more flexible designs that save space, and therefore cut manufacturing costs. The single chip solution also lowers costs for SiS; these cost savings are then passed on to motherboard manufacturers in the form of lower prices. SiS 735 is $10 cheaper than KT266 in bulk shipments.

Connecting the bridges

Like VIA's V-Link bus, which is used to connect the North and South Bridges to each other, SiS has implemented its own proprietary bus to connect the two "bridges". Traditional chipsets used the PCI bus to connect North and South, which is limited to just 133MB/sec. Unlike VIA however, SiS hasn't come up with a marketing slogan for their bus, they simply refer to it as an "Built-in Multi-threaded I/O Link". It may not have a name, but it's certainly no slouch in performance, offering up to 1.2GB/sec between both components. In comparison, VIA's V-Link bus peaks at 266MB/sec. If you're unfamiliar with the North Bridge and South Bridge and how they relate to the components within your system, please refer back to the second page of our VIA KT266 performance preview.

The memory controller

As we mentioned earlier, the SiS 735 chipset supports both DDR SDRAM (PC1600 and PC2100) and SDR SDRAM (PC100 and PC133). Unlike VIA's KT266 chipset however, NEC's virtual channel SDRAM isn't supported by SiS 735. Maximum memory size supported is 1.5GB with up to three DIMMs. This is a little less flexible than KT266, which supports up to 4GB of memory and no more than four DIMMs.

For maximum flexibility, the SiS 735 chipset supports both synchronous and asynchronous memory bus/front-side bus (FSB) operation. For instance, if you have a 100MHz Athlon processor but would like to run your memory at 133MHz, you'd simply select the "100/133" setting in your system BIOS. The asynchronous implementation isn't quite as flexible as KT266; the memory bus can't operate 33MHz slower than the FSB.

The South Bridge

The SiS 735 Super South Bridge is extremely feature-rich. Dual IDE channels are provided with ATA 33/66/100 support, support for up to six USB 1.1 ports, six PCI bus masters (in comparison to five supported on KT266), and like KT266, 10/100MB Fast Ethernet support is provided in addition to one exclusive feature: 1/10MB HomePNA for home networking via phone line.

For legacy audio support, a 2.1 audio controller is integrated with an AC97 interface. (VIA's KT266 chipset offers six-channel audio onboard.)