NVIDIA’s Luciano Alibrandi Dots All "i"
In order to clear everything about the NVIDIA’s Scalable Link Interface out, we decided to make a short interview with NVIDIA’s Director of Product PR, EMEA, Luciano Alibrandi since the most reliable source for information is always official.
Notice the golden connector on the top of the graphics card - that is MIO port.
X-bit labs: For whom do you position the technology? For extreme gamers, or professionals, maybe some other types of users?
Luciano Alibrandi: Both is the correct answer. All professional applications can take advantage of SLI also so Quadro customers will also see significant performance gains.
The SLI technology will provide a huge boost in performance and will allow the hard core gamers to use the highest resolutions and the best filtering all with FSAA turned to the max, thus experiencing a brand new gaming experience. For the professionals we have announced yesterday that the SLI technology will be possible on the new Quadro solutions based on the PCI Express bus. Where applications are significantly bottlenecked by graphics hardware, SLI technology is able to nearly double performance. For applications that are less bottlenecked by graphics hardware, SLI technology still delivers significant performance gains.
X-bit labs: Do you expect dual-card configurations to occupy significant market share?
Luciano Alibrandi: The SLI solution is target at the hard core gamers and high end professional graphics, market size in these areas is relatively small
X-bit labs: How the technology actually works? Does it divide a screen into multiple into multiple parts and then renders, or it works like the original Voodoo2 SLI?
SLI stands for Scalable Link Interface. It is a high performance technology that allows users to combine and scale graphics performance by having multiple NVIDIA GPUs in a single system. SLI works by intelligently scaling geometry and fill rate performance for two (or more) identical boards.
There difference in the way the technology differs from the Voodoo 2 SLI.
- First, 3dfx SLI was implemented on a shared bus using PCI. The PCI bus delivered ~100MB/sec of bus throughput, while PCI-Express is a point-to-point interface that can deliver ~60x the total bandwidth of PCI.
- Second, 3dfx SLI performed interleaving of scan lines, and combined in the analogue domain, which could result in image quality issues due to DAC differences and other factors.
- Third, 3dfx Voodoo technology also only performed triangle setup “down” the graphics pipe, leaving the geometry workload for the CPU, therefore 3dfx SLI hence only scaled simple texture fill rate, and then used inter-frame scalability.
NVIDIA SLI technology is PCI-Express based, uses a completely digital frame combining method that has no impact on image quality, can scale geometry performance, and supports a variety of scalability algorithms to best match the scalability method with application demands
X-bit labs: Is it possible to implement more than two graphics cards using the technology?
Luciano Alibrandi: We are introducing dual GPU scaling only at this time.
X-bit labs: Do all GeForce 6 series GPUs sport the feature, or only GeForce 6800-series?
Luciano Alibrandi: All GeForce 6800 PCI Express cards or Quadro FX 3400 boards support SLI technology. Boards must be the exact same model number and by from the same vendor – for example, two GeForce 6800 Ultras from Vendor XYZ.
X-bit labs: Does the technology require any support from drivers and applications? Will professional applications work correctly and flawlessly with two graphics cards right out of the box? Do you have to certify possible dual-card professional solutions with software makers?
Luciano Alibrandi: SLI technology is application transparent and is enabled through the graphics drivers. All DirectX and OpenGL applications can take advantage of SLI. When two graphics cards are configured with SLI technology, applications will automatically be able to take advantage of performance improvements with no modifications.
X-bit labs: Does the technology rely more on hardware or software (e.g. drivers)?
Luciano Alibrandi: It is a combination of both. We have dedicated scalability logic in each GPU and a digital interface between GPUs to help enable this.
In addition we have a full software suite that enables dynamic load balancing and advanced rendering algorithms that provide the best image quality.
X-bit labs: Have you run into any issues with the technology? E.g., performance anomalies, artefacts, etc? Are they likely to emerge?
Luciano Alibrandi: Not at all. We run extensive testing on our solutions before delivering these to the market.