Windows XP is not supported on the ASRock Z170 Pro 4 - - none of the available drivers will work on XP.
Nothing older than Windows 7 is supported on that board model.
It's very clear to see on the downloads page:
http://www.asrock.com/mb/Intel/Z170%20Pro4/index.us.asp?cat=Download
Maybe you posted on the wrong forum? (This forum is for Windows XP).