Checked the spec sheet from HP (link below) and it doesn't mention beyond 1 HDMI, I would think it's 2.0 because it has the RX580 but that is not definitive. I do know according to the spec sheet that the usb 3.1's are 5gb as they are gen 1 and not 10gb as listed. I bought this laptop and very happy with it so far, I just need to upgrade os drive to ssd, but a great value if you buy it on sale now.
http://www8.hp.com/us/en/images/OMEN_Laptop_17_an012dx_tcm245_2468783_tcm245_2469233_tcm245-2468783.pdf