That's a connector to bridge two graphics video cards. You probably don't have 2 cards to connect; you would know if you did and you would have used this connector by now. It's a special setup to get better graphics power out of your system from 2 cards instead of just one. AMD calls this crossfire technology and NVIDIA calls it SLI. If you do try this, first make sure your power supply is strong enough to run 2 cards. You obviously will need to buy the second card and already have the crossfire bridge (connector) to use if and when you ever choose to do so.