Why it keeps shtting down randomly

My laptop keeps shutting down randomly happens when laptop gets just a little bit hot i feel suspicious about the cooling fan being not fast enough (Which was replaced) or the missing gpu causing the cpu to handle the graphics task (Not sure when) or the "locked by hp" bios setings. However this mostly happens when i run Windows 10 (Which it is came with Windows 8) but doesnt when i run other operating systems like Linux based distros also this is very annoying because it prevents me from using my computer and shut downs when i am doing basic tasks like internet and file browsing or even when i put the laptop on sleep... This also started to happen when it was send to "fix" the laptop and replace the cooling fan i feel like scammed...