What Do MOSFETs Do On a Motherboard? All You Need To Know

Wondering what MOSFETs do on a motherboard, what makes them important, or even why they aren’t talked about frequently despite being such a major component?

Stick around and I’ll explain everything you need to know about MOSFETs, which are actually pretty important to the functioning of your PC, even if they aren’t really spoken about.

What are MOSFETs?

First, let’s establish what a MOSFET even is. MOSFET stands for “Metal-Oxide-Semiconductor Field-Effect-Transistor”, and can alternatively be read as MOS-FET or MOS FET. I’ll be sticking with MOSFET for this article.

If breaking down the name of MOSFET still ended up sounding a little bit like gibberish to you, it’s okay.

The finer details of MOSFETs are more an engineering thing than a consumer technology (PCs, smartphones, etc) thing, even though most consumer technology pretty much relies on MOSFETs, since they’re one of the most common transistor types, in general.

Let’s talk a little about those finer details.

How Do MOSFETs Work in Engineering?

The basic function of a MOSFET is to switch or amplify an electric signal.

There are a few different form factors of MOSFET, but at the end of the day, a MOSFET will be either a Depletion Mode MOSFET, or an Enhancement Mode MOSFET.

A basic power button for switching a device on and off could use both kinds of MOSFET, as a quick example of the applications here.

But let’s not fall too deep out of the PC hardware side of things. After all, that’s what you came here for. What functions do MOSFETs serve on a motherboard?

What Do MOSFETs Do on a Motherboard?

One of the most important examples of MOSFETs at work on a modern motherboard can be found in the CMOS Battery.

The CMOS Battery is a timeless piece of engineering for desktop and laptop PCs alike since it serves the purpose of “saving” your BIOS settings between PC restarts.

In the past, CMOS batteries could actually store this information, but these days they are simply used as a dummy power source for the actual NVRAM chips used to store those settings.

However, the functionality of the CMOS battery hasn’t really changed. By default it’s always in an “on” state, even when you power off your PC, preserving your BIOS settings directly or indirectly.

When you remove the CMOS battery, you’re effectively forcing an “off” state on it or the NVRAM tied to it, which “clears the CMOS” and, by extension, fully resets your BIOS settings.

Another example of MOSFETs at work on your PC can be found when you take a closer look inside the VRMs surrounding your CPU. More on those in a moment!

What is a VRM?

Source: ekwb

A VRM is a Voltage Regulator Module included on every motherboard, used to…well, regulate the voltage to your CPU. VRMs can vary in design from board-to-board, but MOSFETs are a consistent part of any VRM, for engineering reasons discussed above.

MOSFETs are a part of each VRM, and a VRM’s parts also tend to get quite hot under operation, since they’re dealing with a lot of direct voltage before it gets to the CPU (which can already get pretty hot even after the “voltage regulation” is done!).

While VRMs and the CMOS Battery are the two most major examples of MOSFETs at work inside your PC, other components and devices make use of MOSFETs, too.

For example, MOSFETs are also present in the power regulation of a discrete GPU, not just on your motherboard for your CPU.

How do VRMs and MOSFETs Impact Performance?

Now that I’ve explained the purpose of MOSFETs on a motherboard, you may be wondering how they actually end up impacting the performance of your final PC build.

While it would be pretty difficult to account for every MOSFET and other transistor present on your motherboard in PC performance calculations, it actually is pretty easy to draw a line from the quality of your VRM to the performance of your PC.

The main, known benefit of a high-quality VRM (including the MOSFETs within) is improved overclocking headroom. MOSFETs are integral to the CPU power management function of your VRM.

Without the ability to effectively control the power flowing to your CPU, achieving stable overclocks or even maximizing your CPU’s non-overclocked Boost/Turbo frequencies would be pretty difficult.

FAQ

What are Motherboards Made Of?

Motherboards are primarily made of fiberglass and copper.

MOSFETs and their semiconductors are primarily composed of silicon, though. Whenever you hear about a “chip shortage”, that’s usually because silicon or other high-value metals used for these semiconductors are in high price, short supply, or both.

Image Credit: ASRock

Want a more detailed look at the components of a motherboard? Consider heading over to my full guide to learn more about the other components on your motherboard.

Over to You

And that’s all, at least for now!

I hope this article helped demystify the concept of MOSFETs for you and provide an easy-to-understand explanation of how they’re at work within your PC.

Advertising doesn’t tend to focus on such granular details as the MOSFETs, but as this article hopefully showed you, these things do still matter a great deal! You just need to make sure you know why they matter before you let it start influencing any of your buying decisions.

Any more questions about PC hardware or MOSFETs? Feel free to fire them off in the comments section below, and me or another CGDirector Team Member will do our best to help you whenever we see it.

Alternatively, you can also check out the CGDirector Forum to interact with our team and the wider community of experts and enthusiasts who like to hang out on CGDirector.

Until then or until next time, happy building!