what else hardware is needed with antminer s9. Do i need seperate GPU, extra graphics card
You will need a suitable power supply unit (PSU), an internet connection and a device to control the S9. PCs are generally used by miners, often running Linux, although you can use other devices and operating systems. You won’t need any other extra hardware, perhaps apart from things like fans or aircons to keep the operating environment within the parameters required by the S9.