From my understanding the maximum monitors you can run directly from the card is 2 monitors. If you used a DVI splitter then I believe that 2 of the monitors would duplicate the same image / screen. In order to have 3 monitors you need one of the following :
1. add another gpu to your system (if you have available PCI-E slots) although it doesnt have to be the same card and could just be a cheapish model, or upgrade and move your current card to second slot.
2. Grab a 670 or above card (not cheap) as they natively support 3 monitors.
3. Move to AMD based cards as they support 3 screens.
4. Add a Matrix TripleHead2Go device (although I have never used these and know very little about the dynamics / setup / cost.
Personally I would recommend getting a second card if you have space and budget.