What you need to do is go to http://www.google.co.in/, enter the model of your motherboard followed by 'Drivers' then press enter.
Through the magic of the internet you will then be transported to the mystical cave where all drivers are buried.
Alternatively, you can disclose your gigabyte motherboard's exact type here, if it's not a top secret, and someone will help you out with a link (using google.co.in or whatever ).