Sycro

Here's an update on the situation: I noticed a hib(something).sys occupying like 13gb of ssd space, researched on it and turns out its the hibernate/fast boot function of Windows that could be disabled so I disabled it and, somehow, it fixed the problem. Go figure I guess.

Pack up everything except the motherboard, those things can take lots of drops without breaking

No problem,you cant go wrong with either just depends what OS you like 

Source: http://www.pcworld.com/article/3050466/hardware/eat-your-heart-out-quad-cores-intel-just-dropped-a-22-core-cpu-on-us-boom.html 
 
What a beast! Love it. 

sounds like something to do with drivers or something, but yeah those connectors you got were to power it from an older power supply. 

Looked up on how to reset the CMOS on this board. Just cleared the CMOS and it booted on to the BIOS. Not really clear on why the hell that worked but I'll see where it goes from here.

I tested them both on an adapter to connect the MacBook to the monitor. Either way I did go get a third HDMI and still did the same. Now it booted after clearing the CMOS

pc parts picker will automatically pick the best range for most parts. like to example its impossible to choose an 80W power supply and place it in the list with that parts you have. The one you have is good. Power supplys are overlooked vary often here is a video you can watch about them if you want to learn more. 
 

a decent 450w psu would do it too.

You'd be fine with 550w. Unless you plan on putting another gpu in i don't see a reason for going higher.

Okay guys, thanks for the help

Sorry, newbie here, didn't know, so thanks for the tip. I didn't want to spend over 60€ on the PSU, was looking for above 600W and non-modular (purely due to price).