The SLI video card from NVIDIA is a rather unusual solution for increasing a performance of modern computers. Although new technologies make this feature available for anyone, there are some specific issues that require some skills to create a workable SLI pair.
A dual configuration can be created on certain SLI motherboards, such as the ASUS P5ND2-SLI. This motherboard certainly supports the technology. There are some requirements for the SLI video card successful functioning:
-you should have a motherboard with two PEG slots (PCI Express x16) and an official SLI support. Actually, this group includes only the cards on the base of the chipsets nForce4 SLI.
-you must have two identical video cards with a support of the SLI technology. Earlier, NVIDIA announced this feature for the SLI video card GeForce 6800GT and older ones. Therefore, the latest drivers allow to create a SLI configuration even for two similar video cards 6600OLE. It is even not necessary to combine video cards by one producer, only technical parameters matter.
-there should be a SLI bridge on the motherboard. This bridge will be applied by each SLI video card for the information exchange. Currently, this bridge is not required for the GeForce 6600, since these video cards can perform the information exchange via the PCI Express bus.
Having finished with all the hardware devices and settings, you should download fresh NVIDIA drivers. New versions of ForceWare (former Detonator) provide a support for the SLI video card mode.
You should turn a special card on the motherboard for the PCI Express re-commutation for two graphical slots. The card does not contain any specific elements - it is only a kind of bridge. After this procedure you will be able to start a video system with a dual configuration under the Windows XP or Windows Server 2003.
In fact, there are no technical difficulties for switching on two video cards for the chipset Intel 955X. This chipset does not have two ports PCI Express. Thus, ASUS developers found an appropriate solution. They propose using one PCI Express port among some ports of this type, integrated into the chipset's south bridge.
There may be some troubles with the SLI adjustment. Drivers can be the reason and sometimes, the problem cannot be solved only by a software upgrade. The utility RivaTuner can help in such situations. It guarantees an access to the video card registers and keys of its drivers register.
There are some items in the "System" partition of the drivers' settings, which are responsible for the support of multi-chip configurations, including the SLI. The item "MB_Capable" means the compatibility of a certain video card with the SLI technology and the item "MB_Enable" is responsible for switching this support on. If both items are set to "1", then drivers' settings will have a new tab "SLI Multi-GPU". There will be also a menu item for two video cards' working mode "SLI Multi-GPU/Single-GPU/Antialiasing".
The testing of SLI video cards proves that this feature grants a significant increase of the video system performance. Hence, it should be used only when the loading is very high, and its usage will achieve the maximal efficiency. Additionally, the efficiency of the SLI usage depends in an application and mode.