Most desktop computers today have several fans to keep the air flowing on temperature sensitive parts. Mostly your power supply will dissipate the most heat. However the CPU chip itself will dissipate heat and sometimes to a large degree. This requires a heat sink and fan to be applied to the CPU and the main board. Many main boards today have heat sinks permanently mounted on critical chips to provide extra cooling. Maintaining a good temp range will provide the cooler air that those fans need. In the summer for example, if the temp in the room with the computer is 75 degF., the temp inside the PC case will be much higher sometimes around 100 degF or more while running. If the temp reaches 85-90 degF in the room, the main board alarms may sound. Some main boards lack these temperature sensors to monitor with so they may have no thermal protection. If your system does not come with integrated thermal sensing, be aware of the temperature in the room during the summer times. If it's too warm in the room, avoid using the computer until it's cooler.

Your system also has a minimum temperature to maintain. In the winter times, avoid allowing your system to drop below 40 deg F. If your system gets too cold, let it warm up for at least a day before powering it up. Power outages that last for several days can allow the pc to get so cold, the hard disk drive may not startup. Condensation can also be a problem in the cold. Brining a cold PC back into a warm room from a car or garage can cause condensation droplets to accumulate which can damage your equipment.