I'm only level 10 on Typhon at the moment but have SLI working like I said before with 2xgtx580s. I't works on 285-290 drivers, I can confirm that because I've tried all different drivers when switching to triple screens. The only problem I have is extreme overheating with my primary card at 88c when going triple screen and my secondary at 80c, when using single screen they sit at 70c and 62c.
It sounds like a problem with your rig tbh...