Undervolting

=What is Undervolting?= Components have a margin of error in terms of stability. Manufacturers push more voltage in than needed in order to make sure they're stable.

For example, suppose a CPU needs 1 volt in order to perform its tasks. If the CPU gets less than 1V, then it will become unstable and not be able to perform its task because it does not have enough power to do so. So let's say Intel shoves 1.1V into the CPU to make sure it's stable. A slight overvolt will not hurt the CPU, but it will increase the heat output because it is running less efficiently now. The CPU is getting more power than it needs, so it's generating more heat for the same performance. This is where undervolting comes in.

When undervolting, you, the user is doing the work to find the stable point of your CPU in order to maximize its efficiency. The less unnecessary voltage you feed the CPU, the more efficiently it can run (because again, it doesn't need to take in unnecessary power and consequently, heat). So by undervolting, you can feed this theoretical CPU exactly 1V or maybe 1.01V.

Why doesn't intel just feed the CPU 1v from the factory? well that's because every single CPU is very very slightly different, so the exact same CPU model might need 1.02V to be stable, and another might need 0.99V. By giving it 1.1V out of the box, it ensures that all these CPUs are stable, at the expense of lower efficiency.

Here's an example with of an i5-6300HQ, and running AIDA64 without undervolting pulls about 25W of power. After a -150mV undervolt, the 6300HQ can run the same AIDA64 test at 18W of power. That means a reduction of 7W in power consumption and subsequently a reduction in temperatures (remember that processors are functionally 100% efficient heaters).

=How To Undervolt=

CPUs

 * To Do: explain how to do undervolting on Intel CPUs.
 * To Do: explain what RyzenADJ and co. are for Ryzen Mobile CPUs.

GPUs

 * To Do: explain how to do undervolting on Nvidia and AMD GPUs.