nVidia's implementation of SLI Continued
- Enabled by PCI Express
nVidia's SLI method is enabled by PCI Express, namely the upcoming Intel Tumwater server chipset. The Tumwater chipset natively supports dual PCI Express 16x which can be implemented (or not) by choice of the motherboard manufacturer.
You might be wondering why we never saw SLI for AGP from nVidia over the past few years. The answer is really quite simple. There was not much market demand for AGP SLI and as a result, none of the chipset companies bought any products of this nature to the consumer. However, given what I've just said, if nVidia, ATI or any other graphics company wanted to produce AGP SLI solutions, the industry probably would have supported the move, as long as the consumer demand was present. Whenever there is a decent demand for something, IT companies will respond by making the required product available.
You could be thinking nVidia is taking a risk by producing SLI enabled cards as the market for these types of system is very small, since the cost of overall implementation is high. The fact is, it doesn't cost nVidia all that much to implement SLI supporting technology into the latest graphics chips - it's actually been present in nVidia's GPU's for a few years now. nVidia's Add-in-Board partners will be able to decide whether or not they want to add the MIO connector to their GeForce 6800 GT and Ultra cards when they finalize their PCB designs. The cost of this is fairly minimal so you can probably expect to see the majority of PCI Express 6800 GT and Ultra cards from nVidia's Add-in-Board partners to come with the MIO connector, as an added feature.
- Dynamic Load Balancing and Performance Claims
nVidia's upcoming Forceware drivers (probably in the 60.xx range - nevertheless, nVidia SLI driver technology is ready right now and is just itching to be released by all accounts) handle most of the load balancing work for nVidia's PCI Express SLI - that is, the determining of which card will handle what part of the screen. Like the recently announced Alienware dual PCI Express system, at this stage each GPU will be in charge of one half of the screen (top and bottom). nVidia were tight lipped on exactly how this will work but did mention as the technology matures, they will be able to handle load balancing techniques in more advanced and impressive ways.
The good news is nVidia's PCI Express SLI technology "will just work". Meaning, game developers aren't required to release any new patches to support the new technology (at least according to nVidia). nVidia's drivers will take care of the entire process in the background.
nVidia claims performance increases under 3DMark03 up to 1.87 times faster than a single graphics card system. These numbers are based on settings of 1600x1200 with 4x AA and 8x AF.
As you can imagine, the higher you increase the resolution and the higher image quality settings you choose to use with SLI, the faster the performance gain will be relative to non-SLI as GPU performance becomes more critical than CPU and memory sub-systems. Hence the reason nVidia choose these settings but in nVidia's defense, you'd have to be pretty silly to be playing a game at 1024 x 768 with no AA or AF with an SLI system.
nVidia mentioned the typical performance increase you will see is around 60%.
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