ASI Tech Newsletter!

nVidia SLI Ready Video Cards

Would you like to experience the amazing power of two high-end video cards directly linked and working together as a single card?

Now, NVIDIA unveils a revolutionary approach to combining multiple GPUs in a single system to scale performance. NVIDIA® SLI™ (Scalable Link Interface) multi-GPU technology takes advantage of the increased bandwidth of the PCI Express™ bus architecture, and features intelligent hardware and software solutions that allow multiple GPUs to efficiently work together to deliver high performance graphics display on one monitor.

Every high-end PCI Express reference board from NVIDIA will support SLI. The current products that has support for SLI are the GeForce 6800Ultra, GeForce 6800 GT, GeForce 6600 GT, and NVIDIA Quadro FX 3400.

The new NVIDIA SLI video card has advanced compositing, rendering, and scan out technology delivers uncompromised image quality, eliminating the “flashing” effect found in previous solutions. NVIDIA SLI multi-GPU technology also supports both analog and digital output. An intelligent communication protocol embedded in the GPU, and a high-speed digital interface, NVIDIA SLI-based GPUs can easily communicate with one another without the overhead associated with a bus. In addition, a unique software algorithm efficiently shares the workload to deliver extraordinary picture performance.

Each card renders half of the image scan lines which results in double the performance of a single board and the ability to play OpenGL games. To date no manufacturer has come up with a similar concept simply because modern graphics accelerators are all AGP based, there's no dual AGP motherboards and PCI simply doesn't have the bandwidth to handle modern graphics accelerators.

Both 6600 and 6800 series PCI-E cards are connected by means of a SLI, Scalable Link Interface, dubbed the MIO port, a high-speed digital interconnect which connects to a connector on top of both cards. This connector is actually available on all PCI-E GeForce 6800 series graphics cards. Through this MIO port both cards communicate to each other and distribute the workload which is accelerated by dynamic load-balancing algorithms. The screen is divided vertically in two parts; one graphics card renders the upper section and the second graphics card renders the lower section.

The load balancing algorithms distribute the load across the graphics processors. Initially they'll both start out at 50% but this ratio can change depending on the load. Although Nvidia has remained tight-lipped about what makes their SLI implementation tick exactly it is clear that both hardware and software contribute to making SLI work. Most of the dynamic load balancing between the two graphics processors is handled in software and the SLI needs driver support.

Nvidia has told us that prospective performance numbers should show a performance increase closer to 90% over that of a single graphics card. There are a few things that need to be taken into account however when you're considering buying an SLI configuration. First off you'll need a workstation motherboards featuring two PCI-E-x16 slots which will also use the more expensive Intel Xeon processors. Secondly you'll need two identical, same brand and type, PCI-E GeForce 6800 graphics or GeForce 6600 graphics cards.

For workstation users the SLI configuration has a total of four DVI connector so it can display on four monitors and it can be driven off of the respective DVI outputs on the graphics cards. The feature we'll undoubtedly see pitched as a major feature for the Quadro FX version of the GeForce 6800 series SLI configuration. Fortunately they do not require dual Xeons, a single Xeon will work just as well. All in all Nvidia's SLI implementation brings back fond memories of the 3dfx cards days and has all the right ingredients to once again revolutionize 3D graphics provided you're willing and able to pay the hefty price tag associated with it. Nvidia for once again raising the bar and making the harts of many gamers rejoice. The new SLI is here and it looks even better then the 3DFX graphics cards.

NVIDIA SLI Ready	GeForce 6800 Ultra	GeForce 6800 GT	GeForce 6800 non-Ultra	GeForce 6600 GT	GeForce 6600
Transistor count	222 million	222 million	160 million	146 million	146 million
Manufacturing process	0.13-micron	0.13-micron, low-k dielectric	0.13-micron	0.11-micron	0.11-micron
Core clock speed	400MHz	350MHz	325MHz	500MHz	300MHz
Number of pixel pipes	16	16	12	8	8
Number of texturing units	16	16	12	8	8
Number of vertex processors	6	6	6	3	3
Peak pixel fill rate (theoretical)	6.4Gpixels/sec	5.6Gpixels/sec	3.9Gpixels/sec	4Gpixels/sec	2.4Gpixels/sec
Peak texture fill rate (theoretical)	6.4Gpixels/sec	5.6Gpixels/sec	3.9Gtexels/sec	4Gtexels/sec	2.4Gpixels/sec
Memory interface	256-bit	256-bit	256-bit	128-bit	128-bit
Memory clock speed	1.1GHz DDR-3	1GHz DDR-3	700MHz DDR-2	1GHz DDR-3	TBD by board maker, DDR-1
Peak memory bandwidth	35.2GB/sec	32GB/sec	22.4GB/sec	16GB/sec	Varies with memory clock speed

	NVIDIA SLI Ready
ASI SKU		Model	Manufacture	NVIDIA SLI Ready
30912		Quadro FX3400 PCI-E 256MB RETAIL	PNY Click here for link	YES
30913		Quadro FX3400 PCI-E 256MB BULK	PNY Click here for link	YES

With the new arrival of PCI-E things have changed. A number of workstations motherboards featuring the Tumwater chipset will have dual PCI-E-x16 slots making dual graphics accelerators a possibility again. Nvidia steps up to the plate today with the re-introduction of the SLI concept on the GeForce 6800 series, again using the SLI moniker but now with a different approach to the same principles that made Voodoo2 SLI a huge success.

NVIDIA SLI-Ready Motherboard: Supports a PCI Express chipset and includes two physical connectors for two NVIDIA PCI Express graphics cards.