There are couple 900-, 10-, 20-, 30-Series NVIDIA with 5 outputs. 700- and below had up to 4. IIUC it's more like up to (x px, y px) max with up to N independent clocks without external adapters or something along that.
I was doing 5 for no reason from a GTX970 at one point. They just work. But for some reason(segmentation?) NVIDIA brochure pages sometimes disagree or contradict with products in the market.