Mycielski

Are you telling us you're running that CPU overclocked to 4+ on such a low end board that doesn't even have a heatsink on the VRM-s?
Man, you're living on the edge, risking a lot. Your VRM-s must be suffering, a lot. At least add a fan to blow on them directly if nothing else.

Some advice, in no particular order:
1) Most of the advice you will get on this site will be shit, because it's written by people who are also ~15 years old and no life experience yet. Take everything with a grain of salt.
 
2) Don't expect too much from your first job. It will most likely be pretty bad. So your focus should be less on "I want a job for a techie like me!" and more along the lines of "I want a job that's somewhat decent".
 
3) Don't focus too much on your future right now. You're only 14 and your taste and view on things will change dramatically over the next 10 years. What you find fun today might not be fun in 4 years. You might find out that you enjoy other things that you haven't even tried yet. That's why I recommend you don't get too narrow minded and try a lot of different things. School is great in that regard because it usually gives you a little taste of everything.
 
4) Having something as a hobby, and working with that are two very different things. You might enjoy building computers for example, but doing that 8 hours a day, ~260 days a year, is probably really really boring. Especially since it's a low-skill job and therefore doesn't pay very well, and you got a lot of competition in getting those few jobs available.
 
5) I would recommend you start looking into what job you would want to have 15 years from now. This is incredibly hard to do, and the answer you come up with today will most likely not be "correct" (in the sense that you still want it 15 years from now), but it's worth thinking about. If you want to work with computers for example, it's good to start looking into what kind of jobs exist, and what you need to get that.
It's also important to try and think of how much work you want to put in. And by that I mean, being a lead developer at some big company might sound intriguing, but that requires a ton of dedication that not many people want or can put in, on top of a certain personality and a smidgen of talent.
Not all jobs are right for all people, even if that person wants that job greatly. If you are having a hard time in school right now for example, then aiming for a job that requires a huge amount of studying might not be a great idea.
 
6) Spend your youth carefully. While having some work experience is good, your number of carefree, responsibility free days are limited and runs out quicker than you can imagine. There is more to life than just working.

I have this PSU, so far it works great (have it like for a year). It has a premium look and feel to it, and also utilize modern technology (DC-DC conversion, rather then multiple transformator inside).
Yeah, 6+2 pin means, that it is basically an 8 pin, but it's divided in a 6+2 manner, so it can also fit 6 pin.
It has even 2 6+2pin connector, so it should be enough for upgrades.
 
Sparks are not a good sign, in any place inside a computer... That was a heavy warning for you!
You know, these kind of cheap PSU can even cause fire, so it's a potential risk. Always go for a quality PSU and MOBO, that's rule #1.  You can save money on fancy cooling and rgb  not on these parts.

I had the same issue on my Acer laptop, with Intel processor. The following solved the problem for me:
Open the file at /etc/default/grub with gedit (or something else) Find this line in the file: GRUB_CMDLINE_LINUX_DEFAULT="quiet splash" and modify it to this: GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor" Save the file, and exit the text editor. Then run update-grub command in terminal. Then reboot. Hope it helps!

That "good old" office setup tho'...