If rumours about Nvidia’s inability to get a license to produce Intel Common Serial Interface (CSI) bus compatible chipsets are correct, its multi-GPU technology SLI may either disappear from the market or Nvidia may change its SLI licensing policy and open up the technology for others.

At present Nvidia SLI multi-GPU systems may feature two, three or even four graphics processing units (GPUs) by Nvidia Corp. to speed up graphics rendering speed in games. One substantial peculiarity of Nvidia SLI multi-GPU technology is that several graphics cards have to be installed on a mainboard that is based on Nvidia nForce SLI core-logic.

Even though two graphics cards may technically function on any mainboard with any chipset provided that there are several PCI Express x16 slots, Nvidia does not allow system logic sets developed by companies like Advanced Micro Devices or Intel Corp. to power multi-GPU systems carrying two or more Nvidia GeForce-based add-in-cards. In order to enable SLI technology for its Intel Dual Socket Extreme Desktop Platform (DSEDP) Intel had to install certain PCI Express hub chips from Nvidia onto its Intel Desktop Board D5400XS mainboard. By contrast, ATI CrossFire and CrossFire X multi-GPU technologies that allow several ATI Radeon graphics cards to work in cooperation can be enabled on any third-party chipset, but not Nvidia’s (due to prohibition of Nvidia).

Nowadays enthusiasts of high-performance computers and gamers prefer central processing units (CPUs) by Intel due to their high performance. However, Intel does not allow third-party chipset developers to create and sell core-logic sets compatible with its processors without a special license. Currently Intel’s CPUs utilize AGTL+ quad-pumped processor system bus and various chipset designers have license to produce compatible chipsets. However, later this year Intel plans to introduce new so-called Common Serial Interface (CSI) bus for processors, which is similar to AMD’s HyperTransport, but also requires a license.

According to a news-story by The Inquirer web-site, Intel “is refusing to provide Nvidia with a vital piece of CSI technology”, which may indicate that Nvidia loses ability to produce Intel-compatible chipsets late in 2008, which may be a huge blow to Nvidia’s chipset business division.

With no in-house developed Intel-compatible chipsets, Nvidia will have to either allow SLI technology to function on third-party chipsets, or its multi-GPU technology will only function on chipsets supporting microprocessors by AMD, which currently cannot offer the same level of performance as Intel’s CPUs and are usually not gamers’ processors of choice. As a consequence, Nvidia SLI multi-GPU platform may find itself unpopular or may even cease to exist. On the other hand, even if Nvidia fails to get CSI license at any cost, the company may focus on creating graphics cards with several GPUs on them, which do not require any special chipsets.

Not a lot of gamers actually use multi-GPU technologies. Only about 1.5% of Half-Life 2/Counter Strike gamers had a multi-GPU personal computer (PC) with either two, three or four graphics processors, the stats at Steampowered web-site revealed last year. Nvidia’s SLI technology is clearly more popular than ATI’s CrossFire. Steam hardware survey indicated that there are about 96% multi-GPU systmes with two GeForce chips and only around 3.9% - 4.0% machines that feature two Radeon GPUs. According to a recent survey by X-bit labs, about 6% of end-users utilize a computer with two or more graphics cards.

Nvidia does not comment on unannounced products. Nvidia does not comment on business matters. Intel and Nvidia did not comment on the news-story.