3.13.1 System Cooling

Learn the different aspects of system cooling and the components that aid in thermal management in a computer system.

As you already know, heat + hardware = no bueno. PC components will unalive themselves if they feel that the localized temperature (usually denoted in F°, Fahrenheit) Therefore, we much chill PC's out.

Case Airflow

Modern computer cases are designed to create a wind current that pushes hot air out and pulls cool air into the system. The case pulls the air over all of the components from the ones that generate the least heat (optical & hard drives) to the ones that generate the most (CPU, GPU, motherboard, RAM, chipset).

However, an improperly sealed case might cause cold air to escape out the sides of the case, and might allow pockets of stagnant air to appear that never leave. You can resolve this by ensuring that the side panel, I/O shield, and all unused expansion port panels and front expansion are secured and sealed with the case.

Cooling Components

There are several components that create the needed airflow and aid in cooling the computer system.

Case Fans

Most cases only have 1-3 fans at the front. These fans suck cool air into the case. When replacing these fans, ensure that you install them blowing in the right direction. Some cases also have fans on the back or side panel. Fans at the back blow out, sucking hot air out of the system. Side panels typically also suck cool air onto the CPU to keep it cool.

Power Supply Fan

ATX power supplies have big fans in them that exhaust hot air, usually on the bottom of the power supply inside the case. Power supply fans only cool themselves, and they aren't used to cool any other part of the PC.

CPU Heatsink & Fan

Since the CPU is usually the hottest component in a computer, they get their own dedicated cooling component. During a PC's uptime, the CPU sits at around 85-150° F, but during resource intensive activities it can reach 190°!

The heatsink is usually made with a heat-conductive material like copper or aluminum, and they sit directly on the top of the CPU to draw the heat it generates and dissipate it. The fans of the heatsink increase the surface area, allowing more air to be drawn by the cool air circulating in the PC.

Passive heatsinks are heatsinks that don't have a fan. They're usually used on high speed memory modules, most motherboard chipsets, and low-end GPUs. High-end GPUs always use an active heatsink.

Liquid Cooling

When NASA PC owners don't have enough cooling for their system, they employ liquid cooling to support the array of fans installed in the case. It uses a series of hoses connected to a radiator to move heat away from components and cool them off. Liquid cooling is really expensive, so only high end systems have it.

Heat Sensors

There are an array of heat sensors on the motherboard that monitor internal temperature levels.

• CPU sensor - located on the circuit board underneath the processor
• System case sensor - located either on the motherboard or on a cable attached to the motherboard
• Room temperature sensor - connected to the motherboard through a cable; mounted on a case slot

Recommendations

Because proper airflow is necessary to keep components cool, consider the following recommendations to ensure optimal system cooling.

• Keep the case free of dust and debris. Excess dust can restrict airflow and prevent proper heat transfer.
• Reduce the number of airflow obstructions.
  • Employ proper cable management (i.e., bundle cables together and secure unused cables to the case).
  • Space multiple hard disk drives instead of stacking them next to each other.
  • Do not use an excessive number of expansion cards.
• Maintain appropriate ambient temperatures. Optimal ambient temperatures are between 60 and 80 degrees Fahrenheit. For server rooms, the ambient temperature might be as low as 45 degrees.
• Ensure proper ventilation.
  • Keep air intakes and exhausts free from obstructions.
  • Leave space between the computer and any walls or desks.
• Preserve negative pressure inside the case by keeping all covers and shields installed (e.g., unused expansion cards, I/O shield, front drive bays).

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