Ok, to start with you need to know which drivers are not installed. On win8.1 press 'WindowsKey + X" to open the advanced context menu. Click "Device Manager" and then post a screenshot of what you see there. Specifically, you're looking for items with yellow exclamation marks next to them.
Nine times out of ten, you're going to find all the drivers you need from the mobo manufacturer website. A quick google search should take you straight to the download page.