SLI and dual monitors question

Hi everybody

Since I managed to snare an unused G1 Sniper 3 MB for A$80 (!), I thought I'd give SLI a go, and have got another 660ti on it's way to me. I run 2 monitors for FS9 (hey, I like it, ok? ), do I hook up a monitor to each card, or leave both on the card already fitted? I use the second monitor for FMCs, etc.

Thanks in advance, Chris