PC green screening/restarting itself.

Over the last couple of months my PC has started green screening when playing a game and restarting. I have seen this could be an issue with my GPU but I'm not sure tbh.

Therefore this post is seeking advice really in two parts.

1. Any ideas on what the issue could be? I will include my specifications here:

CPU - AMD Ryzen 7 3800x
GPU - Sapphire Pulse Radeon RX 5700XT
MOBO - Asus ROG STRIX B450-F Gaming ATX (AM4)
RAM - Corsair Vengeance DD4-3200 RAM 32GB
PSU - Corsair CV650W
CPU Cooler - Corsair H100x Liquid Cooler
OS - W10 64bit
Storage - Sabrent 1TB M.2 SSD, 1TB Samsung Evo SSD, 2TB Seagate Barracuda HDD

2. If it is the GPU, would it be best to just upgrade the full rig or just focus on a couple of upgrades? If so any recommendations.

Any advice or recommendations would be really great thanks :)