This article provides two ways to update and download the ASUS BT400 driver. You can use a reliable driver updater, such as EaseUS DriverHandy. Or you can download it from the ASUS website. Step 1. Find the USB-BT400 download in ASUS Download Center and click 'Driver and Utility.' Step 2. Select the system version of Windows and click 'Download.' Step 3. Find the downloaded file and follow the instructions to install ASUS USB BT400 driver.