I have two gtx 580's in sli. well at least I think I do.. In the Nvidia Control Panel sli is enabled. So both cards are pny 1.5gig 580's. Now the Problem is that in Lavalys Everast ultimate edition is only showing only one video cards memory? Is that a problem or something that is normal. This is my first sli setup.
If you have 2 gtx 580s with 1.5gb vram each it doesn't give you a total of 3gb vram. It does almost double your performance, but not the actual ram. This video explains it pretty well: http://www.youtube.com/watch?v=BlXlczDEAXs
So both of them are working and being used? I saw when I was playing bf3 It was dropping.
If in the nvidia control panel you have "maximize 3d performance" checked then yes, it should be working. if you want to be 100% sure just take out one card, play bf3 and see what kind of fps you get, then put in the second card and compare it it.