It really is just one thing after another with games development and computers generally, I have never come across this type of behaviour in my life but I think I have managed to fix it. I ran into an issue in the past couple of days where if I tried loading up games the game would freeze and then bring up a solid colour on the screen like this one. It then seems to crash entirely and then automatically restart, causing the computer to complain about not shutting down properly even when you get into windows.
I was very worried this was a sign that the graphics card was dying or the power supply, after talking to various people and realising it would just be case of having to take out components and find out what worked and what didn't I had a brain click. As far as I've known, graphics cards don't normally cause outright crashes when they're dying unless they're going horribly wrong, very often they get buggy first and you can still run games but they develop what's called artefacts on the screen which will be things like purple bits on grass and foliage and things like this as the card desperately tries to render things in full colour but fails.
So the only possible conclusion given that power supplies generally make a computer behave horribly when they go or shut off altogether would be that it's the RAM, I cynically popped out one of the RAM components and noticed there was a nasty smearing of dust on the RAM slot. The reason I suspected it was the RAM was because even on windows the PC was misbehaving even when everything was fairly idle, so I popped both my RAM components out, gave the slots a bit of a clean, put them back in and then success!
For now at least, I'll have no choice but to do some stress testing to make sure, but I seem to have saved myself the trouble of buying new components and swapping them in just by giving the computer a thorough looking over, Skyrim and a benchmark test so far have worked without issues.
I just thought I'd write this down because if you ever see this suddenly pop up on your screen and your PC crashes, check your RAM, the colour will also vary depending on what you run, I've had variations of pink and purple, even blue when I ran the benchmark software I was using.
Small Update: So far I managed to play PUBG without any issues, yay!
Update 2: So it looks like I've spoken too soon, I've fixed the worst of it and it takes awhile before the crash happens but I know exactly which memory stick is causing the problems, so what I'm going to do is go and buy some fresh RAM tomorrow and put it in to see if that fixes the problem permanently.
Update 3: After testing it looked like both my RAM sticks were failing, so I've simply replaced them with a new one that's 8GB and matches up with what I've had before, so far, I have not experienced any problems and even managed to have a bit of a gaming session, I'm going to have to just keep stress testing it though and I guess have mandatory gaming sessions now to try and see if this has indeed fixed it.
So there we go, if this all works, solid colour screens popping up when you do stuff and a computer being forced to restart is a sign of dying RAM. I think one of my RAM sticks was failing more than the other which is why when I took one of them out it lasted a bit longer before causing the computer to crash.
Update 4: GOD DAMNIT! Yes, this is the classic problem of trying to troubleshoot issues with a PC, so things are a bit more stable now, but ultimately I still ended up crashing while gaming, I can at least do more now and I don't think windows will be an issue anymore with the fresh RAM, so it could be worse than just the RAM failing but the GPU as well.
It looks like tomorrow I'll have to go through the annoying process of RMAing my card and seeing what the manufacturer can find out about it.