you're wrong!
IF it's overheating, something is mostly with tons of dust on it, or poor cooling to start with, either way, a game won't hurt your system, since it uses less processing power then mostly benchmark out there...they, they indeed use the whole system to is maximum.. A GPU intensive game like GTA with graphics mods like ENB + HD textures, can increase temperature, shouldn't hurt the hardware tho, (if operated in right/safe conditions) but could increase the temps for sure..
U could Download a software like RealTemp(intel CPU's) or CoreTemp(AMD CPU's) to check CPU's Temps...and GPU-Z for your's GPU Higher temp CAN and WILL even KILL your hardware...
Again, not a mod, game or software problem at all...it yours problem to fix the hardware...or clean the dust out of it!
As for high usage of RAM, that's nothing, i have, mostly of the time more then 13GB loaded, sometimes without any game open at all... IT IS MADE to be used! Servers have huge amount of RAM being used!
That been said, you should check to avoid any further problems! Good Luck for ya