Idk why this wasn't mentioned in the video when discussing Windows 8.1 but AMD graphics cards past RX series do NOT have driver support for Windows 8.1, which is the reason why I myself had to 'upgrade' from 8.1 to Windows 10
First time I installed a GPU I didn't realise I had to plug in the 6 pin connector and spent the day thinking I'd killed it when I got a black screen. The first time I then built a PC I forgot to put in the motherboard standoffs