The What's and Why's of undervolting - TUXEDO Computers

What is CPU Undervolting?

CPU undervolting is the targeted lowering of the processor's supply voltage and thus, simplified, the opposite of overclocking.

What are the advantages of undervolting?

• The power consumption of the processor is reduced and the energy consumption is lower.
• This allows the fan to spin slower and the battery runtime also improves minimally. 
• In addition, the overall performance can increase under high load because the upper temperature limits are only reached at a later point.

Which processors support undervolting?

AMD's mobile processors do not currently offer this option. With Intel, undervolting was disabled via the firmware in 2020 due to an exploit called Plundervolting. Meanwhile, some system providers, including TUXEDO Computers, enable undervolting again in some models. At TUXEDO, these are:

• InfinityBook Pro 13 v4
• InfinityBook Pro 14 v4
• InfinityBook Pro 14 v5
• InfinityBook S 14 v5

With Intel's Tiger Lake generation undervolting does not work.

What is there to consider when undervolting?

The values that can be set in the mentioned notebooks are in the harmless and safe range. Nevertheless, you should not set the maximum right away. In the BIOS under the menu item  CPU Core & Cache Voltage Offset the value of -50 mV (millivolt) is preset on some notebooks and works without problems on every supported processor. However, if you want to go lower, you should do this in small steps.

Practical procedure

If you want to lower the preset value of -50 further, first go to -60, save the setting and test extensively after a restart whether the system runs stably. If so, you can set the value to -70 if necessary and repeat the test. If your system does not run stably at -70, for example, you know that -60 is the maximum value for undervolting on your device.

A recipe can't be created here because every processor reacts differently to the undervolting settings. This is because transistors in microprocessors don't always switch at exactly the same voltage, but within a limited voltage tolerance range. Thus, it can happen that two identical notebooks only allow -60 on one, while the other runs stably with -80.

What happens when undervolting is set too low?

If the voltage reduction is too low, the computer may "miscalculate", i.e. the software may deliver incorrect results or no longer run correctly. Physically, no damage occurs, as long as you proceed in steps of 10. After the voltage has been raised again, everything should work as normal.