The SiS649 supports a front side bus that operates at 800-MHz and the DDR memory interface at clock frequencies of up to 400-MHz and DDR2 memory interface at clock frequencies up to 533-MHz and the PCIe 16x graphics port. The SiS649 works with two dual-in-line memory modules for a total of 2-Gbyte of system memory, SiS said in a statement.

The SiS649 requires a second chip to form a complete chipset, SiS said, suggesting its own SS965, which provides PCI-E x1, gigabit LAN, eight USB 2.0 ports, AC97 7.1 channel sound, 4 SATA and 4 ATA ports.

The only difference in the SiS656 is that it supports a DDR2 memory interface of up to 667-MHz suggesting that the SiS656 is just a speed-binned version of the SiS649, but it would then hardly justify its own part number.

The SiS649 is available in sample quantities and motherboards including the SiS649 are expected to start appearing in September 2004, SiS said. No mention was made of any expectations for the SiS656.