NVIDIA SLI Interview


posted 9/10/2004 by John Yan
other articles by John Yan
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When Alienware displayed their Video Array system, I was wondering when someone else would be releasing a product with a similiar feature. NVIDIA didn't take too long to unveil their SLI solution. With that, we talked with the Desktop Graphics Product Manager at NVIDIA, Steve Sims.

GamingNexus: What is your reaction to Alienware’s announcement knowing you had SLI in the back of your pocket and only letting it out in the recent month?

Steve Sims: We are working very closely with Alienware and are extremely excited that they are pushing multi-GPU technology forward.

GamingNexus: I’ve heard that Alienware did consult with you when they were developing their Video Array technology. Were they ever aware of your plans to incorporate SLI technology in the PCI-E GeForce 6800 cards?

Steve Sims: Clearly, enthusiasts PC builders are key customers for SLI technology, so we brought in our key partners very early in the process. We were working very closely with Alienware and will continue to do so.

GamingNexus: While the Alienware technology isn’t currently in production, they claim there’s a 50 – 100% increase in performance depending on the article you read. What is NVIDIA’s estimate on how much of an increase you can get in your technology?

Steve Sims: The amount of performance improvement will depend on the application. In some circumstances it is up to a 2X increase in performance. We expect performance to scale almost linearly, and in general, performance gains will be best with applications and modes that tend to be most graphics limited, i.e, higher resolutions with higher levels of antialiasing and anisotropic filtering. We should note that the current performance numbers that Alienware has announced do not reflect any of the dedicated scalability logic, inter-GPU digital interface or dynamic load balancing software of SLI.

GamingNexus: How long has SLI technology been in the works?

Steve Sims: Graphics chips back to GeForce 3 have supported multi-GPU configuration, but we did not enable it until recently.

GamingNexus: What were some large hurdles you had to overcome when doing R&D?

Steve Sims: NVIDIA SLI can intelligently combine and scale graphics performance by having multiple NVIDIA GPU’s in a single system. SLI works by intelligently scaling geometry and fill rate performance for two GPUs. So getting the right algorithms to balance the workload and get maximum performance was the key. There are several methods that can be employed to improve performance when using SLI Technology and the NVIDIA drivers utilize the most appropriate method depending on the needs of the application. At the most basic level, inter and intra-frame scalability algorithms are supported. Details of the specific algorithms are NVIDIA Intellectual Property, so we can not go into much detail.
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