Multicore systems are vulnerable to thermal covert channel attacks as the increased power consumption may remain undetected, while occurring alongside normal, CPU-intensive applications. The purpose of this work is to study thermal effects on modern multi-core systems and decrease the possible risk of attacks. In this research, by controlling the fan speed, we have tried to decrease the temperature of the system to an appropriate level to fight these kinds of attacks. The results indicate that when the temperature decreases to a considerable level, lower power consumption is achieved.