Originally Posted by
MiRai
Unfortunately, 2GB + 2GB doesn't equal 4GB in this case. You only have 2GB at your disposal at any one time. SLI mirrors the memory across each GPU, it isn't additive (nor is it used for buffering another GPU). If you shut off SLI, you have one single underclocked GTX 680 with 2GB of RAM. I know you mention this later in your post which I didn't quote, but I just wanted to point this out for anyone else that browses through this thread and selectively picks things out of it.
That's just more marketing bullshit. It's marketed that way the same way that its memory is marketed. You have so many CUDA cores per GPU and they only work together when the GPUs are SLI'd; but again, SLI doesn't exactly double/triple/quadruple your performance as they'd like you to think -- Especially while multiboxing.
Of course you have a choice, turn off SLI in the control panel and let the other GPU sit there idle.