I had Intel core 2 duo E6750 and i swapped it with Intel core 2 duo E8600. By doing that it makes squeaking noise, but if is processor working at minimum 50 percent that noise stop. My PC is completely stock, and i looked in a manual of my pc and that core 2 duo E8600 is fully compatible with my pc, please help me, thanks.
You are with the computer, I can only give you ideas but you have to physically check and eliminate what it is or what it is not.
You might simply need to tighten the cooling solution fan shroud. It could be a fan bearing that is squeaking and when your system drops to 50%, the active fan control slows down the fans, and the squeak stops.
Heck, it could be a mouse chilling with a martini and sunglasses on a little mouse size lounge chair. 🐭🐭🐭