You're going to use GTX 590s in SLI ... and that's the board you choose? Don't go cheap like that. If you want to stay with Gigabyte, you need to go with one of the Z68X-UD4/UD5/UD7 versions.
No, that board doesn't support SLI of any kind. It does support CrossFire, but only in a crippled way. You need to look for a board that will do x8/x8 for SLI and CrossFire instead of x16/x4. Or even go with one of the few boards that will do x16/x16 SLI or CrossFire, like the UD7 board I mentioned above.
Wait wait wait......... Your gonna put a 700 dollar graphics card into a cheap board, with an i3, and 4 gigs of ram?!!!!! You need to get your priorities straight. You obviously have more money than brains. you need to split your graphics card budget and get a nice mobo, i5 or higher, and 8gb of ram and maybe even a SSD. That 590 would do you no good if your limited by a crappy little i3 and 4gb of ram. just get a 580 or 2 560ti's. That would be plenty of graphics power, unless your making Avatar 2 on your computer. You put a 590 in a computer that has equally high performance parts. Putting a 590 in a computer with an i3 is like buying a Ferrari motor for your Ford Pinto. Don't cheap out on your processor or MOBO. I'm not trying to be a jerk, This post just blew my mind a little.