Keep in mind this is also dependent on motherboard as well. The motherboard manufacturer determines which iGPU outputs are present, so double check that as well.
If the motherboard supports iGPU triple screen, it should advertise the feature. I know the Asus Z87 Deluxe (this is the board *I* would get with haswell
, in particular, supports it while some of their budget boards do not! Just a heads up, make sure the board works with it.