Hey Remiel! Please ensure all the ribbon cables and cables are connected properly. I would recommend retracing your steps to ensure you did everything correct, as well as tighten up the screws in an X pattern which is done by tightening one corner, the the one diagonally across it. As sherlanmamaril said you should try using the spread method to ensure full coverage of the CPU and GPU on the PS3. Alternatively you can you thermal pads. Also should note thermal paste is non-conductive so it shouldn't harm any of the sensitive electronics. Here is the iFixIt PS3 Slim thermal paste replacement: Cómo reemplazar la pasta térmica de Playstation 3 Slim