Test Setup and Methods, and nForce 680i SLI

We tested G80 using the latest high-end enthusiast core logic from NVIDIA, nForce 680i SLI. The top Intel version of its nForce 6-series chipset family, 680i debuts today at the same time as G80 and G80 board SKUs. We've not had the chance to formally evaluate the board used to house 680i, but first impressions are absolutely excellent. The board is extremely performant, matching and often besting everything we've come across to date for Intel LGA775 microprocessors, and the effort put into its engineering at the board level and in the BIOS have it standing, in our eyes at least, as the enthusiast core logic of choice.

NVIDIA have engineered what effectively amounts to a production-quality reference board, entirely in-house, and will be selling it branded via traditional NVIDIA-only graphics board partners such as eVGA (vendor of the board we have for testing), XFX and BFG. Traditional NVIDIA mainboard partners such as ASUS and MSI will likely engineer their own 680i SLI efforts using their own layout choices and peripheral ICs. The reference board sports 6 SATA2 ports, 10 USB2.0, 2 hardware-level GigE network ports, three PCI Express x16 slots (16-16-8 configuration) and a layout that makes concession for the GeForce 8800 GTX in terms of availability of ports and connectors when two 8800 GTX boards are installed. In short, we like, and it was a stable platform for all of our testing.

Testing Methods

For our architecture analysis we use a mix of software, largely biased towards our own in-house tools but with a healthy selection of freely available others. Our own self-written shader programs are run using in-house frameworks based mostly on Cg or MDX, along with raw ASM shader input to D3D9. You'll see us refer to what we used and how we tested as the architecture analysis progresses, and you can freely ask us anything about how we test if there's a detail you need to know via the Beyond3D forums.

It's a unique and highly fruitful way to see what a chip is capable of, and the first departure from how we've done it in the past. The architecture analysis revolves around instruction rate testing using our own issuers, to calculate throughputs and investigate execution limits of the shader core, whatever they may be. We've also written AA sample pattern detectors, floating point filter testers and fillrate benchmarks to help analyse G80 in GeForce 8800 GTX configuration.

Myself and Arun Demeure are chief architects of the vast majority of the tests used for this analysis. We also use contributed and freely available tests from George Kolling, Ralf Kornmann, Victor Moya, Mike Houston and pals at Stanford, and also the guys at iXBT/Digit Life in order to poke and prod, and the big help of all the guys in Team Beyond3D and silent friends to make sure we're doing The Right Thingâ„¢.

We forge on then with an overview of the architecture before diving in at the deep end.