What are Motherboard Power Phases?

Last Updated on November 6, 2020

When setting up a new computer, most users care about the bigger things like the Motherboard and the CPU to go with the device. Often, regular users would not give much thought to the amount of power that the CPU uses or what regulates it.

However, as we will see, knowing how much power is consumed by a CPU is crucial and to go deeper into that, we need to know what are motherboard power phases.

Motherboard power phases stand between the computer’s Power Supply Unit (PSU) and devices such as the CPU and the RAM. They reduce the power that the PSU outputs to a lower value that can then go to the mentioned devices.

This ensures that the components such as the CPU receive just the right amount of power they need as going too high or too low can be problematic.

What is VRM?

Known as the Voltage Regulator Module, a VRM is a circuit on a motherboard that’s composed of many different phases that step down the voltage from the power supply.

The VRM ensures that a stable power supply is provided to a CPU, therefore ensuring its longevity and optimal performance.

Since many modern CPUs require about 1.5 Volts or less to function, a good VRM is necessary to ensure that the limit is not topped.

VRMs get very hot during operation because a lot of the voltage that gets dropped is converted into heat. To reduce the negative impacts of high temperatures such as reduced performance, a heat sink is often used on some of the hotter parts of a VRM.

A VRM on a Motherboard with Liquid Cooling
A Section of a motherboard showing the Chokes and Capacitors along with a cooling setup covering the MOSFETs. Source: asus.com

Also Read: What is VRM on Motherboard

What are Motherboard Power Phases?

Motherboard power phases are composed of several components that work together to step down the voltage to a usable value for the CPU.

The composition of the components may vary slightly from one board to another but the function remains the same.

A single motherboard can have several power phases connecting to one CPU.

Theoretically, the more the phases you have on your motherboard, the better the performance of the VRM. This is because the entire workload is shared equally among the phases.

For more clarity, if a motherboard has four phases leading to the CPU, each of the phases will be up and running for 25% of the duration of time that the CPU is in operation, likewise, if you have eight phases, then each will be running for just 12.5% of the time.

This has significant benefits for the system as improves the lifespan of each phase and also improves the stability of the CPU.

The quality of the motherboard phases depends on a lot more than the number of phases you have. The phases also need to be constructed with high quality and high tolerance materials, especially because of the heat that gets produced during their operation.

Composition of Motherboard Power Phases

As mentioned, several different components work together to form a single power phase. Although the composition might be different, MOSFETs, Chokes, and Capacitors are used to make up a single phase.



The MOSFET (Metal Oxide Semiconductor Field Effect Transistor) plays a huge role in the phase.

It along with its Integrated Circuits communicate with the CPU and gets information about the amount of voltage that is required.

It also identifies the voltage that is being received from the PSU, thereby processing how much of it needs to be shed off for it to be the proper magnitude for the CPU.

In older designs, the MOSFETs and their drivers were separate components on the motherboard, however, advancements in technology have allowed a more compact design whereby the transistor and its drivers are packaged into a single chip on the motherboard.

The MOSFETs on a motherboard’s power phase are the most susceptible to high temperatures since they carry out most of the voltage dropping. Because of this, the heat sink on the VRM will often be covering the MOSFETs to keep them cool.

They are largely impacted by things like overclocking and if you need to overclock your board, then an after-market cooling system should be on your mind to keep things nice and cool.

What are Motherboard Power Phases?
The Mosfets as depicted here are the black ICs behind the protruding cube-shaped Chokes. Source: tipsmake.com

Also Read: How Hot Can a Motherboard Get

The Chokes

A basic choke, aka inductor.

Up next, we have the choke. A key ingredient of a steady and stable power supply is to minimize the jitters in the electrical signal.

You wouldn’t want your CPU to get a voltage that spikes all over the place since it can cause system instabilities if you’re lucky and if not, you may burn the CPU.

The Chokes are in place to ensure that you do not get unstable voltages.

There are many different kinds of chokes used on motherboards. For users who intend to push their CPUs to their limits, investing on a high-end motherboard with high-quality chokes like Super Ferrite Chokes (SFCs) will greatly improve the performance of each single power phase.

It is standard procedure to infer the number of power phases that a motherboard has by counting the number of chokes around the motherboard.

In standard conditions, this can give you a good estimate, however, in some cases, motherboard manufacturers may deceive customers by increasing the number of components on a motherboard without necessarily increasing the actual number of phases.

The Capacitors

The main function of a capacitor is to store charge. In a motherboard power phase, these components help to smoothen the voltage, making it more stable and usable in the CPU.

Capacitors used in a phase need to be high-quality ones and should not leak. Some poorly constructed electrolytic capacitors tend to get weaker with use over time and leak when they get old. Unsurprisingly, this can damage your computer.

Additionally, a faulty capacitor in a power phase can introduce some voltage instabilities that can cause damage to your system.

The capacitors are usually visible next to the chokes and since they don’t generate a lot of heat the heat they are usually uncovered by the heat sink.

Different Types of Capacitors
Capacitors on a motherboard come in varying shapes and sizes. Source: geeksinphoenix.com

Types of Motherboard VRMs

As mentioned earlier, motherboard VRMs provide power for both the CPU and other components like the RAM.

In VRM marketing, you will find something like a “6+2” or “12+1”. This is called phase design. It refers to the configuration of phases and the first number before the ‘+’ is the number of phases (VRMs) dedicated to the CPU whereas the second number is the number of phases dedicated to other devices like the RAM.

Cheap VRMS that are made of low-quality components tend to fail or underperform. With expensive boards from reputable manufacturers, you’re more likely to land a device with enough phases to provide stable power for overclocking.

Which brings us to our final point:


VRMs and power phases do not matter much to the general public until you decide to overclock.

When you overclock, it directly puts burden on the VRMs as they now have to regulate a higher amount of voltage. Regulating a higher voltage also generates more heat.

In this situation everything from the number of phases to the size of the heat sinks and the quality of the capacitor starts to matter.

For this reason, on expensive motherboards, you will notice they have a high number of power phase design (higher amount of VRMs) and with premium sub-components like larger heat sinks.


If you were wondering what are motherboard power phases then you now have a good idea about what they are and their functions.

They are necessary because the 12 or so volts that are provided by a Power Supply Unit is higher than what components like the CPU and RAM need. They reduce this to a manageable level and further assist in smoothing it out, therefore, making it stable.

The phases are composed of multiple components that work together to supply the CPU with adequate power.

If you want a high-performance board for a high-performance CPU, consider getting one with adequate high-quality motherboard phases.

Atif Qazi

Atif Qazi is the founder of PCGearLab. He is a PC enthusiast as well as engineer with a keen interest in PC hardware and all stuff related to tech and games.



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