Hi all,
Apologies if this is a simple/recurring question but I'm fairly new to owning a PC (especially for gaming.)

My Specs are:
- Intel® Core™ i3-9100F Processor
- NVIDIA GeForce GTX 1650
- 8GB DDR4 RAM
- 1TB HDD Storage
https://www.currys.co.uk/gbuk/computing/desktop-pcs/desktop-pcs/pc-specialist-vortex-ar-gaming-pc-intel-core-i3-gtx-1650-1-tb-hdd-10199161-pdt.html is the link if there is any crucial info I am missing.

Every time I play a game (Black Ops III was the first to have issues) I get crashes where a large amount of the textures on screen go either blue or red, and the PC either freezes like that or reboots. Most of the time it freezes and I have to manually reboot. To begin with this would happen randomly and infrequently, but it is now at the point that it happens within 10 minutes of loading any game, even ones that aren't particularly resource demanding.
Another issue that I have had (but only one) is that when I booted up the whole screen was covered in lines of green pixels, this only happened once and was solved after a couple of reboots but may be relevant?

Any help would be greatly appreciated!