VIA's K8T900 Chipset
Dual PCI Express with RapidFire
Back when the K8T890 was introduced, VIA introduced the DualGFX Express technology which would allow two PCI Express Graphics cards on a single system. The goal was to offer a single PCI Express x16 slot along side a secondary PCI Express x4 slot for enhanced multi-monitor support. This implementation would allow applications to be accelerated on both cards while supporting up to four monitors.
With the K8T900, VIA dropped the idea of a dedicated PCI Express x16 and secondary x4 PCI Express graphics slot in favor of a more balanced approach with RapidFire. The K8T900 chipset provides two PCI Express graphics connections with 8 PCI Express lanes per connection, or 16 PCI Express lanes when one card is used, similar to the nForce 4 SLI configuration. Additionally, with VIA's tweaking of the PCI Express implementation, VIA claims graphics performance increases of 3 to 5% when compared to the competition, namely the nForce 4, when running high-bandwidth graphics solutions.
We mentioned earlier that VIA's dual-PEG implementation was similar to the nForce 4 SLI, so much so that VIA utilizes a very similar transposer card to alter the lane configuration on their reference board. This doesn't mean the board is SLI or Crossfire capable, however. The hardware implementation is in place and VIA sees no reason for SLI or Crossfire not to work. In fact, VIA's own in house testing has shown it should work with supporting drivers. However, the two technologies have not been validated to function on the K8T900 by ATI or NVIDIA thus far, leaving the ball in NVIDIA and ATI's court.
There is one multi-GPU implementation that the K8T900 has been validated to work with, that being S3 Graphics MultiChrome technology. MultiChrome is an open-platform technology that allows two of S3's Chrome S27 graphics cards to function together on any motherboard equipped with two PCI Express graphics slots, regardless of chipset. S3's approach is to have two Chrome S27 cards run together by using a multi-GPU driver set rather than relying on hardware connections between the two graphics cards.