Having GPU and/or CPU related errors

Hi everyone! I'm new here. I mostly just "read" forums to get knowledge but now I need your help personally.
So here it goes;

I built a new PC a few months ago with the specs written on my profile. It was fine at first had some Hard drive issues but fixed it by replacing it right away. After few weeks I decided to get BF4 to play and after opening the game I've got the "The driver stopped responding and recovered" So I've tried almost all of the solutions provided in forums that is related to the software side. Didn't help. I could play 2d games and watch videos etc. but not that game. After a while I changed that GPU with another and now It's doing it so random I have no idea what causes it. Later then with the frustration I re-formatted the computer and stuff, as long as I don't install the GPU's driver (old or new doesnt matter tried almost all) I'm fine.

That was the first problem. The second is;

After all of this I've had everything downclocked and had less crashes since. BUT WAIT THERE'S MORE!
While playing a game or using CPU+GPU for around 20Mins the screen goes black (no signal) the comp freeze and the sound goes something like (gerrrrrrrrrrrrrrrrrrrrrrr- well repeating the last sound ofc.) and It doesnt go to the BSOD afterwards. It stays like that as long as I don't reset it.

And that feels like (somehow) a PSU failure a sudden drop of voltage or something? Anyways The event viewer shows a Kernel-Power stuff and I dont know what to do

Sorry for a story like post and thank you.