Alright so, after investigating my issue on Google, going through random settings, contacting the HP support centre, and calling over a few friends who are good with PC's, I have finally realized what the issues are.
So, firstly, the geniuses at HP thought that making the heat pipes of both the CPU and GPU connected (and putting them extremely close together) would make a wonderful idea, especially for a gaming laptop with such a strong central processing unit. My friends who work on laptops for a living have stated that such a thing, especially for gaming laptops, is one of the worst you can see. But that isn't the full reason as to why it's overheating.
Secondly, most gaming laptops are apparently designed to perform better when plugged in. Hence why my FPS would always drop to 20-30 when unplugged. After doing some tests, it was determined that for some reason, the laptop was designed to (mostly) maintain the CPU's frequency at 3907 MHz, sometimes reaching the maximum of 4007 Mhz whilst playing games due to something called the "Intel Turbo Boost Technology", which can be considered similar to overclocking.
Nonetheless, I will still be purchasing two new, stronger fans, as well as adding some quality heat-conducting paste for both my CPU and GPU, and will see to acquire a cooling pad as well, for longer gaming sessions. I'd like to thank you all for helping me on this thread but it seems like there was no problem after all, people @ HP are simply retarded.
TL;DR Don't buy
gaming Laptops from HP, they obviously don't know how to make them, and choose your future PC's carefully.