One of the major features inherent to the nForce 700a series of chipsets is support for Hybrid SLI. NVIDIA's Hybrid SLI technology gives users the ability to pair an IGP, or mGPU (motherboard GPU) as NVIDIA calls it, with a discreet graphics card, or cards, for two new modes of operation. NVIDIA calls these new modes Hybrid Power and GeForce Boost.
GeForce Boost does what its name suggests. By coupling the motherboard's integrated GPU with a discreet graphics card, the 3D rendering workload is shared between the two GPUs for a boost in performance. Currently, GeForce Boost is only supported by GeForce 8400 GS and 8500 GT discreet cards, as for the IGP, the GeForce 8x00 and nForce 7x0a series will be supported initially, although new IGPs for the Intel platform that support Hybrid SLI are slated to arrive as well.
Hybrid Power mode is also fairly self explanatory. With a monitor connected to the mGPU, the discreet graphics card can be almost completely shut down to reduce power consumption when not in use. A side effect of the reduced power consumption will also be reduced heat and potentially less noise output from the system. The discreet card is shutdown (or enabled) using the SMBUS connection inherent to the PCI Express graphics slots. We should also note, that Hybrid SLI is supported by both PCI Express Gen 1 and Gen2.
NVIDIA's Hybrid SLI technology is controlled by system status and the Window Vista Power Plan. Hybrid Power, for example, is enabled when the system reaches an idle state to reduce power consumption. We spoke with NVIDIA back during an early briefing and asked if an auto-switching system based on applications or workload for GeForce Boost and Hybrid Power was in the works, and company representatives explained that they would like to enable this type of functionality, but that it wouldn't be ready upon initial release.
As it stands today, a new control panel icon in the system tray will give user's the ability to configure Hybrid SLI for other modes of operation. Because a Hybrid SLI system will have multiple GPUs installed, it's also possible to run multiple displays.
As has been the case for their last few high-end chipset releases, NVIDIA has designed a reference platform for the nForce 780a SLI.
NVIDIA's reference nForce 780a SLI platform exploits all of the features inherent to the chipset and has a slot configuration that allows for 3-way SLI configurations. We didn't test a reference board in this article, but have seen them running at a number of events. Instead, we tested a few retail-ready motherboards, that we'll show you on the pages ahead.