Deliding is the process of removing the IHS (Integrated Heat Spreader) from the CPU with some methods described below which aim to drop CPU temperatures. Since Intel Series 3, 4, 6 and now 7, Intel uses a black silicone type to glue the IHS to the PCB, but the die barely touches it. And Intel uses a poor kind of thermal paste too, so there's very poor contact between the die and HIS, resulting in bad heat dissipation, thus a hot CPU.