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What Is Undervolting a GPU or CPU, and When Should You Do It?


CPU power supply circuit on a motherboard.
Skrypnykov Dmytro/Shutterstock.com

You’ve probably heard of overclocking in the context of computers, where systems are pushed beyond their factory-approved settings. Yet not all modifications are about making your system go faster; undervolting is the art of restricting the flow of power.

What Is Undervolting?

Just like any electronic component, a CPU or GPU requires an electric current to flow through it. Voltage is essentially the measurement of the “pressure” with which electrons flow through a circuit. When you undervolt a CPU or GPU you’re reducing that pressure, which has an effect on the energy available for that processor to work.

The idea behind undervolting is to find the optimal minimum voltage that a processor can use without causing performance losses or instability. This is at least as tricky as pushing voltages upwards to make overclocking more stable but without any of the danger.

Why Undervolt a CPU or GPU?

It’s one thing to explain what undervolting is, but that doesn’t explain why anyone would want to do it! The answer to that question is somewhat more complex and part of it involves how voltage relates to power and heat.

First, processors essentially turn electricity into heat. As the electrons move through the integrated circuits of the processor driving all that math, they make heat. This is why a CPU needs a cooling solution because if it gets too hot it will stop working!

Power consumption is measured in Watts and the basic formula for wattage is Watts = Volts x Amperes. If you lower either the Volts or the Amps, you’ll reduce the total Watts. That means the processor will use less power and make less heat.

Reducing power consumption is a good reason to undervolt and this is why it’s popular on laptop computers. Since it can make your battery last longer by drawing less power from it. Reducing heat is also important since it can curb thermal throttling, allowing a processor to run at higher clock speeds for longer.

Undervolting also puts less pressure on the processor’s power phases, which step down the voltage to a level where the CPU can use it. In theory, this should help stability on lower-end motherboards, but in practice, this doesn’t make a real difference.

With both GPUs and CPUs, slightly better performance along with lower power consumption and less fan noise is possible, but performance gains aren’t the primary reason to do it.

What Makes Undervolting Possible?

If a CPU or GPU is designed to run at a particular voltage (or range of voltages), why does it still work when you undervolt it? There are two parts to the answer here, the first being the nature of processor production.

Processors are etched out of silicon wafers using a process known as photolithography. This is one of the most precise manufacturing processes in the world, but there are still tiny differences in each CPU’s quality that affects how well they run.

Processors are “binned” into certain performance classes, and all that pass validation are guaranteed to run at a specific voltage and clock speed range. Within that group of CPUs, some will happily run at lower voltages than the official specification. The same happens with overclocking, where the “CPU lottery” sometimes nets you a processor that can safely reach clock speeds reserved for much more expensive components.

You may be lucky enough to have a desktop to laptop CPU or GPU that happens to run well on lower voltages than it’s supposed to. In this case, you can save power, reduce heat, cut the noise, and maybe get a few more FPS in games.

How Is Undervolting Done?

TechPowerUp interface on a Windows PC.
TechPowerUp

There are two ways to adjust the voltage of a CPU. You can use the BIOS or UEFI menu to adjust the CPU’s settings at a firmware level, or you can use a software utility from within your operating system. For example, the Intel Extreme Tuning Utility or ThrottleStop.

The software method is the most practical way to find your perfect voltage since you don’t have to restart the computer every single time you need to make changes. Once you’ve found the perfect voltage, you may want to lock it in from the firmware settings, however.

For GPUs, your only option is to use a software utility such as MSI Afterburner. You’ll have to set the utility to apply the settings each time the computer starts up, but in practice, this isn’t much of a hassle.

Should You Undervolt Your Computer?

There are two parts to answering the question of whether you should be undervolting your PC. The first is the risks involved. Broadly speaking, the risk that you’ll damage your computer through undervolting is effectively zero. It can be distressingly easy to kill a CPU or GPU by putting too many volts through it, but the opposite should be harmless.

You do, however, run the risk of having an unstable system if the voltage is too low, and that can lead to data corruption. So, as always, it’s a good idea to back up anything that matters before attempting to modify your computer.

As long as you know how to reset your motherboard settings to default if it doesn’t boot (check the manual) or you know how to boot into Safe Mode, there’s no real reason to avoid undervolting if you have the time and patience for it.

RELATED: What’s the Best Way to Back Up My Computer?





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