http://www.amazon.com/Gigabyte-GeForce-Graphics-GV-N970G1-GAMING-4GD/dp/B00NH5T1MS/ref=sr_1_1?ie=UTF8&qid=1420732435&sr=8-1&keywords=Gigabyte+GeForce+GTX+970+4GB+WINDFORCE+Video+Card
http://www.amazon.com/Gigabyte-GeForce-Overclocked-Graphics-GV-N970WF3OC-4GD/dp/B00NH5T1UA/ref=sr_1_2?ie=UTF8&qid=1420732435&sr=8-2&keywords=Gigabyte+GeForce+GTX+970+4GB+WINDFORCE+Video+Card
What makes these cards different?
http://www.amazon.com/Gigabyte-GeForce-Overclocked-Graphics-GV-N970WF3OC-4GD/dp/B00NH5T1UA/ref=sr_1_2?ie=UTF8&qid=1420732435&sr=8-2&keywords=Gigabyte+GeForce+GTX+970+4GB+WINDFORCE+Video+Card
What makes these cards different?