NVIDIA Linux SLI Primer
To begin, we have what is at the heart of any reliable computer system - the motherboard. At the time of writing, NVIDIA has certified 12 SLI-capable motherboards that use the nForce4 SLI Intel Chipset, while there are 22 officially certified for the nForce4 SLI AMD Chipset, and 4 motherboards for use with the nForce Professional AMD Chipset. In addition, there is presently one SLI certified motherboard from ASUS for the nForce4 SLI X16 Intel and a second ASUS motherboard for the nForce4 SLI X16 AMD Chipset. When it comes to Chipsets it is also important to note some manufacturers such as Epox, Biostar, and ASUS sell i945P-based motherboards with two PCI Express x16 slots and a PCI-E bridge, however, there is no current SLI support on alternative Chipsets until NVIDIA decides to enable the support through its drivers. For those that are unfamiliar with the SLI certification program, it is a process by which NVIDIA weeds through various motherboards, graphics cards, power supplies, and even some system memory in an effort to find the most reliable and high quality parts to distinguish them from the mediocre components. The rigorous screening process replies upon tests that focus on diagnostics, benchmarking, burn-in, and card interoperability. For reference, ONLY products that have passed the actual NVIDIA SLI certification program can be called 'NVIDIA SLI Ready', whether it is a power supply, motherboard, memory, or a graphics card. Although we have experimented with numerous SLI Ready motherboards, now that the official Linux drivers are expected to launch shortly, you can expect to see some SLI motherboard reviews now appearing on Phoronix. The SLI compatible motherboards we've sampled thus far have been from Abit USA, ASUS, Tyan, and DFI. For those enthusiasts who wish to support Linux-friendly manufacturers, Tyan has released their first AMD nForce4 SLI motherboard, the K8E-SLI (S2866), which is expected to pass the NVIDIA certification process with excellence. We have had the Tyan S2866 for quite some time now and are overall incredibly pleased, we will have a Tyan K8E-SLI review for posting shortly after the official Linux SLI launch. For this guide, however, we went with an Albatron K8SLI. This SLI-certified motherboard boasts the nForce4 SLI AMD Chipset with a Socket 939 interface on the motherboard.
Launched recently has been the SLI X16 variant of the nForce4. Previously when running Scalable Link Interface it was required that the two PCI Express x16 NVIDIA cards actually run at x8 speeds for each connection, but this latest Chipset revision removes this x8 performance cap thus allowing each graphics card to run at their full x16 speeds. Through using this latest NVIDIA Chipset, Gigabyte has managed to engineer a QUAD SLI motherboard solution, which, as the name implies, allows four NVIDIA GeForce cards to run in SLI while at x8 PCI Express speeds. Although we're uncertain at this time whether or not the Gigabyte 8N-SLI QUAD Royal will truly ever reach mass production, the capabilities of this NVIDIA Chipset are definitely fascinating. One aspect to keep in mind while choosing an SLI capable motherboard is the spacing of the two PCI Express x16 connectors. This spacing is often important if you're considering using after-market cooling and for general cooling constraints. Although required in most situations, is the SLI bridge for connecting the two SLI cards, which allows for up to a 10GB/s transfer rate and keeps both cards in sync. Another component found on most SLI-capable motherboards is a SLI selector card for switching between single and dual graphics cards. Finally, it is vital that if you plan to purchase high-end GeForce PCI-E cards for use with SLI that you also accompany it with a fast processor to reduce the CPU bottleneck that can likely occur.