NVIDIA's Tiny 90nm G71 and G73: GeForce 7900 and 7600 Debut

Quad SLI and Purevideo

Today NVIDIA is also putting its Quad SLI initiative into action. Unfortunately, it doesn't look like they will be selling add-in Quad SLI based cards in the near future, but for those in need of such a setup will be able to find them from various system builders. Obviously this is a little at odds with the enthusiast community who prefer to build their extreme rigs themselves, but NVIDIA cites thermal, space, and power concerns not easily addressable by the individual as a reason for pushing out this hardware to system builders first. How many power supplies out there can provide enough power for SLI and CrossFire, let alone have the headroom to support four GPUs? Similarly, thermal issues could definitely be a problem in a case without good air flow.

NVIDIA would not commit to any timeframe for bringing Quad SLI to the add-in market, but they did indicate that they want the requirements for Quad SLI to be clear and readily obtainable by an individual. The landscape does have to be ready for something like this. Even if an enthusiast could put together a thermal solution to support Quad SLI, most of us don't dabble in power supply design and manufacture on the side. Unfortunately, we don't have any Quad SLI cards to test out either, but we are certainly looking into getting our hands on a system. We will have benchmarks as soon as we are able.

Quad SLI will provide a few new modes that are basically extensions of what the current SLI technology offers. Split frame rendering (SFR) will now split the frame 4 ways, and alternate frame rendering (AFR) will support one GPU rendering every 4th frame. The latter mode will provide the most benefit in games that support it as geometry processing will be well divided among the GPUs. Additionally, AFR of SFR will take each frame and split it among a pair of GPUs. Each pair then renders every other frame. This mode will be compatible with all titles that currently support AFR. Additional SLI AA modes will also be added to take advantage of up to 32x AA.

The Quad SLI is setup using what NVIDIA calls an x48 PCIe interconnect. This takes the x16 connection from the motherboard and both video cards and manages all 3 at full speed. In this way, full use can be made of available PCI Express bandwidth, both to and from the system and between GPUs.

Last week NVIDIA also launched an update to their Purevideo driver which is supposed to deliver increased performance and support, specifically for H.264 video playback. We will also be looking into updating our video quality and performance tests with the new Purevideo driver as soon as possible. The biggest change we would like to see from Purevideo is a free download from NVIDIA. Currently requiring users to purchase more software in order to get full functionality of advertised features fomr their hardware is more than a little disappointing.