Taipei, Taiwan - Now that the track has been laid for PCI Express, Taiwan's chip set makers are steaming ahead with a lineup of silicon for the interconnect standard.
Intel Corp. is expected to launch its PCI Express chip sets sometime in April, and Mellanox Technologies Inc. has already announced Express-based chips (see www.eetimes.com/story/OEG20040209S0023). The Taiwanese players say they will match or possibly beat Intel's schedule in the hope of stealing a little market share from the chip set leader.
Via Technologies Inc. and Silicon Integrated Systems Corp. already have samples of north- and south-bridge chips, and plan on volume production at the end of March. ULi Electronics Inc., a subsidiary of the ALi Corp. unit of Acer, will follow a month or two later.
In general, the chip sets from the Taiwan-based suppliers offer similar functionality. All are bringing leading memory technologies to the PC, such as dual-channel DDR at 266, 333 and 400 MHz and DDR2 at 400, 533 and 667 MHz. Front-side-bus clock rates hit 800 MHz on Intel's Pentium platform and 1 GHz on Advanced Micro Devices Inc.'s platform. That's about where the similarities end.
Intel's i915P Grantsdale and i925X Alderwood chip sets will include x16 links for graphics and support for DDR at 333/400 MHz and DDR2 at 400/533 MHz. They reportedly will not support the AGP8X interface. Intel's ICH6 south-bridge chip will have four PCI Express x1 links, four serial ATA150 ports and the company's upgraded sound technology. Dubbed Azalia, it brings 192-kHz, 32-bit multichannel audio support to the PC.
Different route
To differentiate itself from Intel, Via is taking a different route with its north-bridge silicon. While all three Taiwanese chip set makers are offering x16 implementations of PCI Express for graphics cards, Via will also include AGP8X support.
Via believes the transition to PCI Express for graphics will be relatively quick. Nevertheless, for maximum flexibility it is maintaining legacy AGP support, which will likely involve a die penalty and increased power consumption.
Like Intel, Silicon Integrated Systems (SiS) and ULi will not offer AGP support, mostly because they are less willing to increase die size. Interestingly, ULi said it would leverage AMD's HyperTransport link to include AGP8X support in its K8 south-bridge chip.
Via is running a x4 link off its north-bridge chip for high-speed networking or high-bandwidth storage devices. Its new VT8251south bridge will also include two x1 PCI Express links, four serial ATA ports, Gigabit Ethernet and eight-channel, 192-kHz, 24-bit audio.
SiS is content with only the x16 link in its Pentium 4 north bridge, the SiS656. However, because AMD's Athlon 64 FX and Opteron CPUs include a memory controller on board, the SiS north bridge will have enough room to include a x4 link. The company is still uncertain about whether it will update its Rambus chip set with PCI Express.
The first-generation PCI Express south bridge from SiS, the SiS965L, will have two x1 links, to be followed later in the year with four x1 links, the company said. The first iteration will also include eight-channel audio, two serial ATA ports (moving on to four) and Gigabit Ethernet support.
ULi will include a x1 link into its north bridge for the Pentium 4, and will do a south bridge that also supports two x1 links, Gigabit Ethernet and eight-channel audio.
Although they are all supporting PCI Express in the south bridge, none of the chip set makers sees a big need for it at the moment, especially in mainstream desktops.
"With the exception of Gigabit Ethernet, there really aren't many peripherals connections that can utilize the bandwidth of PCI Express right now," said Ben Boyden, marketing manager for Via's chip set division. "For example, an eight-channel sound card is fine with the bandwidth it's got on PCI as it is now. But in graphics, they will eat up that bandwidth very quickly." Soon "serial ATA 2 IP is coming, and that is 3 Gbits/second," said ULi marketing manager Bruce Tai. "We will definitely need a high-speed bus interface to support it."
