Various SLI Modes

SLI can function with the following modes:

Split Frame Rendering (SFR): In this mode, each frame is split into two and each half is sent to a different GPU for processing.

Alternate Frame Rendering (AFR): Instead of splitting a frame into two, the graphics cards will now each process an alternate frame. When the first GPU is render the first frame, the second GPU will render the second frame concurrently.

SLI Antialiasing (AA): The antialiasing feature in a single graphics card can only go up to a maximum of 4x. In SLI AA mode, the system is now capable of handling up to 8x, 16x or 32x (for certain GPU). In a quad SLI system, it can even go up to 64x. Since the main purpose of antialiasing is to improve the images quality, setting the system to run at 32x SLI AA will not see any improvement in the game speed. Rather, with a big monitor, you will get to enjoy far superior graphics quality.

Quad SLI System

A quad SLI system means that there are four GPUs inside a computer. It can be in the arrangement of 4 graphics cards in parallel (utilising 4 PCI-Express 16x slots), or 2 dual-GPU graphics cards in parallel (utilising 2 PCI-Express 16x slots).

Quad SLI did not show any massive improvements in gaming using the common resolutions of 1280×1024 and 1600×1200, but has shown improvements by enabling 32x anti-aliasing in SLI-AA mode, and support for 2560×1600 resolutions at much higher framerates than is possible with single or dual GPU systems with maximum settings in modern games. It was believed that high latencies severely
marginalized the benefits of four GPUs, however much of the blame for poor performance scaling is due to Windows XP’s API which only allows for a maximum storage of 3 extra frames. Windows Vista is not limited in this fashion and shows promise for future multi-GPU configurations.