NVIDIA Single Card, Multi-GPU: GeForce 7950 GX2

Introduction

Today marks the launch of the first GPU maker sanctioned single card / multi-GPU solution for the consumer market in quite some time. Not since Quantum3D introduced the Obsidian X24 have we seen such a beast (which, interestingly enough, did actual Scan Line Interleaving on a single card). This time around NVIDIA's flavor of SLI and PCIe are being used to connect two boards together for a full featured multi-GPU solution that works like a single card as far as the end user is concerned. No special motherboard is required, the upcoming 90 series driver will support the card, and there is future potential for DIY quad SLI. There is still a ways to go until NVIDIA releases drivers that will support quad SLI without the help of a system vendor, but they are working on it.

For now, we will take a look at the card and its intended use: a card using a single PCIe connection designed to be the fastest NVIDIA graphics board available. While there are some drawbacks of SLI still associated with the 7950 GX2 (certain games scale less than others), the major issues are quite nicely resolved: there is no need for an SLI motherboard, and it's much easier to make sure everything is hooked up correctly (with only one power connector, no SLI bridge needed, and only one card to plug in). The drivers start up and automatically configure support for multi-GPU rendering, and (after our motherboard's BIOS was flashed) we had no problem with the system recognizing the new technology.

While the potential for quad SLI is a reality, the usefulness is still fairly limited - only users with ultrahigh resolution monitors will see the benefits of four GPUs. At lower resolutions, CPU overhead becomes a factor, and some limitations of DX9 come into play. We certainly want to test quad SLI on the 7950 GX2, but we will have to wait until we get the equipment together and track down a driver that will support it. In this article, we will compare the 7950 GX2 with other high end NVIDIA and ATI cards, and we'll also take a look at how well it scales compared to it's close relative: the 7900 GT / 7900 GT SLI. But before we get to the benchmarks, let's take a look at how NVIDIA puts it all together in a way that avoids the necessity of an SLI motherboard or an external power supply.