Heat Management

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Before you start

Objectives: learn why is cooling so important when dealing with modern PCs, and which components generate most heat.

Prerequisites: no prerequisites.

Key terms: air, cooling, component, fan, cpu, heatsink, case, temperature, hard, hot, pc, memory, power, room, system, video, airflow


Heat Detection

CPUs, memory, hard disks, etc., generate large amount of heat. Most modern CPUs have a heat sensor built in that the BIOS and the motherboard can use to report current temperature. With most CMOS programs we can actually go in and see what the current temperature of the CPU is. Applications that run on top of the operating system on the PC can also access that information from the BIOS and display a message on the screen indicating what the current CPU temperature is. Processor sensor is located on the circuit board underneath the processor. Beside the CPU, there are other components in the system that create a lot of heat, such as the hard drive, memory, and even the video board. It is possible that those other components are running too hot too. To check overall PC temperature we can implement an inside-the-case sensor which we mount to the case chassis. That sensor detects the temperature of the environment inside the PC case. If we work with critical systems such as servers, we can also implement a room temperature sensor. This tells us how warm the air outside the PC is. If the room temperature is too high, our PCs can also overheat. If we blow hot air onto the hot components, we don’t get much cooling.

Fans

Usually the fan implemented in the power supply is sufficient to keep the components cool. However, on a heavily used system or a system that has lots of components, it’s possible for this fan to be inadequate.

Power Supply Fan

Image 304.1 – Power Supply Fan

In that case, we can mount extra fans on the case chassis itself that will blow additional air into the system. Most good quality chassis will have a spot where we can mount one or two extra cooling fans. We differentiate intake and outtake fans. Intake fans create airflow by either blowing or sucking airflow across the motherboard and components. Outtake fans pull warm air from inside the system. On many systems, the power supply fan performs either intake or outtake functions. Remember that with an ATX or BTX system, we draw air from the outside and we blow it into the case. In this way, we push air right over top of the hottest components.

Case Fan Example

Image 304.2 – Case Fan Example

We should always keep the cover on the PC system, and we shouldn’t have any open expansion slot covers. The computer case is actually a pressurized system with a carefully-designed path for air to flow. If we have the case cover off, or if we have an open expansion slot, it creates a path for the air to flow, so our components don’t cool properly. It’s also important that we make sure that our power supply fan and any auxiliary fans have proper airflow from the outside to blow into the case. Fans are also used in conjunction with heat sinks to improve cooling.

Dust

One of the main problems with heat management is the the fact that the dust will collect inside of our PC. We should always ensure that the dust is not preventing air flow trough power supply fan and any other fan. We should clean them and other components from dust on regular intervals, especially if our computer is on the floor all the time.

Hottest Components

The hottest components in the PC are the CPU, the memory, the video board, the chip set, and the hard disk drive. The CPU typically has two different cooling methods implemented. At the top of the CPU we will have a heatsink. The heatsink touches the CPU so the heat is conducted from the CPU into the heatsink. Heatsink will typically be made up of bunch of fins, which increases the surface area of the heatsink. This allows more air to flow over it so the heat dissipation is more efficient. With heatsink we always have to use the thermal paste to increase the heat’s ability to flow from the CPU into the heatsink. Some heatsinks will have a thermal pad that provides the same function. We need to make sure that there’s good heat conductivity between the CPU and the heatsink. To cool modern CPUs we also have to use a fan together with a heatsink. The fan is put on top of the heatsink to keep our CPU cool. Without it, our CPU would burn up in a matter of minutes.

Heatsink Fan Cpu

Image 304.3 – CPU Heatsink with Fan

The memory in a system can also get very hot. To deal with that we can implement heat spreaders on our memory modules to dissipate heat.

Memory Heat Spreader

Image 304.4 – Memory Heat Spreader

One other hot component in the system is the video board. Because of the amount of RAM and the because they have their own CPU, video boards can generate a large amount of heat. Video cards can have their own heatsink and a fan.

Heatsink and Fan on a Video Card

Image 304.5 – Heatsink and Fan on Video Card

Another hot component in our system is the chipset. Our northbridge, southbridge combined chipset can have it’s own heatsink and a fan on top of it to dissipate the heat. Another hot component is the hard disk drive. They’re quite away from the power supply fan, so we shouldn’t stack the hard drives right next to each other if possible. We should leave a space between them so that the air can circulate through. There is an option to implement a hard drive cooler which will dissipate the heat from the hard disk drives. Hard drive coolers are often a set of fans that attach to hard drives. On most desktop systems we don’t see that very often, but we will see it on server systems. Also, older internal IDE and SCSI cables were flat and could restrict the airflow inside the case. To maximize cooling, we should keep cables organized and consider using rounded cables to maximize airflow.

Server Cooling

When talking about servers we must manage the temperature of the room. If we blow hot air from the room into the server case, it won’t provide the cooling effect that we need. Servers should be put in a server room which has air conditioning to esure constant room temperature. Air temperature should range roughly between 70 and 74 degrees Fahrenheit (21 to 24 degrees Celsius). Sometimes this is not enough, and if so we can implement liquid-based cooling. Liquid cooling system cools the components using a liquid instead of air, and it is used on extreme systems which generate tremendous amount of heat. Liquid cooling is the best cooling method, but it is also the most expensive. That’s why we don’t usually see it on workstations, except maybe on gaming systems.

Remember

CPUs, memory, hard disks, etc., generate large amount of heat. Modern CPUs have a heat sensor built in. To check overall PC temperature we can also implement an inside-the-case heat sensor. With an ATX or BTX system, we draw air from the outside and we blow it into the case. One of the main problems with heat management is the the fact that the dust will collect inside of our PC. The hottest components in the PC are the CPU, the memory, the video board, the chip set, and the hard disk drive. The CPU typically has heatsink and a fan. We can implement heat spreader on our memory modules.

Author: cicnavi