Now, I would like to remplace the bios because the one the motherboard comes with (A random Acer motherboard btw)
lack in the overclocking department, and I'm quite sure I could squeeze some mhz out of this CPU.
So that's why I'm curious to know if I could remplace this crappy bestbuy bios, by let's say, a bios with more overclocking abilities.
Not likely. Most newer boards have the bios chip soldered on; most bios files won't flash to a different board; it's a failsafe mechanism designed to prevent you from having a dead board from flashing the wrong file. It's safer to change out the motherboard, and if necessary, get a new windows coa for the new board. Gateway, like most oem systems, has a small bios file with the windows keycode. Your windows copy most likely won't load with a non Gateway motherboard.