Windows Update is generally pretty good about picking up drivers, but for things like graphics cards, it does poorly.
You'll want to go to the manufacturer's website (either Nvidia or AMD). From there, you navigate to support/drivers page. If you know the exact model of graphics card and operating system, you can manually enter that data, then you'll be provided with a link to download the right driver.
If you're not sure what graphics card you have, there's a auto-detect tool that can be of use.
Now then, for your motherboard's drivers, it is a similar process of obtaining the correct and necessary drivers. On Gigabyte's website > Support/Downloads enter your model of motherboard and you'll then be able to download the drivers you...