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Graphics Memory & SLI - Everything you need to know
Dear Mad Mod Mike,
If I have two GeForce 6600GT 128MB cards hooked up in an SLI configuration will video games use 256MB of video RAM? I ask because an article at Guru3d says that the video is "cloned" from one card to another and that video games cannot use the video memory as if you had a single 256MB card.
Confused,
Jeffrey
This is a common question Jeffrey.
Guru3D is correct. The graphics memory is NOT doubled in SLI mode. If you have two 128MB graphics cards, you do NOT have an effective 256MB. Most of the games operate in AFR (alternate frame rendering). The first card renders one full frame and then the next card renders the next frame and so on. If you picture SLI working in this way it is easy to see that each frame only has 128MB of memory to work with.
If you feel you need 256MB or even 512MB of graphics memory for certain games, then you need to make sure that each card has that much memory. Also keep in mind that if you mix a 128MB GeForce 6600GT with a 256MB GeForce 6600GT that BOTH cards will operate with 128MB of graphics memory (the lowest common memory size of the two cards).
Another misconception is that the GeForce 7800 GTX (256MB) graphics cards and the GeForce 78000 GTX 512 graphics cards can be paired together. Since these graphics cards use different GPUs, they unfortunately CAN'T be paired together. Always refer the Learn More or Build sections of SLIZone. SLI works for graphics cards within the SAME GPU category. Here are the GPU categories again:
