I have bought a rx 480 and installed it but it does not work. It runs but i am stuck with intel graphi
You are going to need to be way more descriptive than that if you want help. Post your full System specs and what troubleshooting you have done.
You would need to disable the onboard Intel graphics and set the Radeon card to be the card that boots for starters as well as making sure your power supply is actually connected and upto the job of working with the GPU.