VIA K8T900 AMD Chipset Preview
Introduction to the K8T900
The last year has been a tough one on VIA's chipset department. Delays of their new south bridge and a lack of vendor support for their north bridge chips have left the AMD enthusiast crown on the heads of NVIDIA's nForce4 chipsets. It wasn't always like this; when the K8 first made its appearance, the K8T800 and K8T800 Pro chipsets were widely accepted as the best option for an Athlon 64 platform. The nForce3 chipset was the best offering NVIDIA had at the time, and though it wasn't a bad product, it offered nothing over VIA's K8 series in terms of performance and VIA had a definite price advantage.
The beginning of the end of VIA's dominance in the K8 chipset marketplace came with the release of the nForce4 chipsets in October of last year. The NF4 platform brought 1 GHz HyperTransport support, new networking and storage technologies, overclocking support and of course, SLI. Even the fact that VIA announced their K8T890 chipset with PCI Express support before the NF4's arrival couldn't help them as their south bridge, with all the new features, was continually delayed.
Well now that south bridge is ready, and even has a slightly improved feature set since the last time we "previewed" it.
The K8T900 North Bridge
VIA's latest AMD-platform chipset has been dubbed the K8T900. Targeted at pretty much all levels of market including professional, enthusiast and mainstream segments, VIA is once again going to try to take back market share they have lost.
VIA plans on doing this with a host of new improvements to the chipset: outstanding performance, premium features, support for dual graphics card implementations, pin-compatibility with the K8T890 and support for all current and future AMD CPUs. Sounds impressive. If they can pull it off, they might just succeed where they had failed in the past year.
The first feature VIA has on the K8T900 is something called "RapidFire" technology that claims to increase PCI Express graphics performance for high bandwidth cards. A reduction in latency and improved signal quality over the K8T890 will help with the performance claims but VIA also says they have reduced the power consumption of their PCIe implementation.
What does RapidFire actually do? Unfortunately, we weren't able to find out for sure from anyone! This rather vague diagram provided with the press kit seems to show VIA's PCIe implementation using two separate PHYs; one for each GPU on their dual-graphics motherboard.
Speaking of dual graphics support, VIA has gone one step further in hopefully supporting both SLI and CrossFire on this chipset, in addition to VIA/S3's own MultiChrome technology. The chipset has support for either a single x16 PCIe connection or two x8 PCIe connections that will allow for enough bandwidth for SLI and CrossFire to technically function.
There is a lot more to this process than just creating a board with two x8 slots as NVIDIA and ATI both now have certification programs that are a requirement for a motherboard or chipset to pass before their drivers will 'allow' SLI/CrossFire to run. We saw this scenario a long time ago when the K8T890 was first released with two x16 PCIe slots (one running at x16 and one running at x4) but this was not up to NVIDIA's 'standards' for SLI. This prevented VIA from selling SLI-ready motherboards because the NVIDIA GPU drivers would not allow SLI to function on anything non-certified. This time around though VIA will be submitting their boards to NVIDIA's GPU department for certification in hopes that SLI-ability will be enabled.
This process has not yet begun though due to VIA's reluctance to submit an unreleased/unannounced chipset to NVIDIA, who also happens to be a competing company on that front. I was told that after today (Nov 22, '05), NVIDIA should be receiving samples very soon. I assume this applies to ATI and CrossFire as well.
Of course, besides the multi-GPU rendering support that VIA is striving for with the K8T900 chipset, the two x8 PCIe slots are also going to allow VIA to offer a wide array of multi-display features. Four monitors are easily achievable by attaching nearly any PCIe graphics card into any of the 16x slots.
Besides the x16 or two x8 PCIe slots for graphics cards, the K8T900 north bridge also offers support for four additional lanes of PCI Express as either four x1 slots, or one x4 slot. That gives boards based on the K8T900 a total of 22 lanes of PCI Express and 5.5 GB/s when coupling it with the 8251 south bridge chip. Motherboard vendors can use these PCIe lanes for attaching integrated peripherals like Gigabit LAN connections or they can allow for expansion slots directly on the north bridge that provide a lower-latency connection to the memory and processor than PCIe lanes going through a south bridge first.