What the heck is undervolting?
While many of you may be familiar with overvolting a GPU as part of the overclocking process, undervolting is as it sounds, the exact opposite. Higher voltages often lead to increased heat and obviously higher power consumption, and depending on your use case; this might not be ideal. Factory overclocked GPU’s are usually a prime candidate for undervolting. The overclocks applied at manufacture can often be sloppy and decrease the thermal performance of your GPU without giving any noticeable performance gains.
The main reason most people would consider undervolting their GPU is if they are continually running into thermal throttling. Thermal throttling is where the GPU reaches its peak operating temperature, and so the clock speeds are reduced to help with cooling. This translates to stuttering, frame drops and all sorts of nasty surprises. Some users may find that they are throttling way too often, and an undervolt can often be seen as a good fix.
One benefit often lauded at the humble undervolt is increased GPU lifespan. By running your GPU at a lower voltage, you will be easing the strain on it. This could then lead to an increased lifespan, although there is no hard and fast rule to how much of an effect this will have.
Reduced power consumption
Reducing the voltage will reduce the power your GPU draws, but not by much. I don’t really see the benefit here, if running costs are an issue for you then make sure you do your research when buying a new GPU to find the power consumption/performance sweet spot.
Fixing clock speed issues
Some users have even used undervolting to fix clock speed issues. In this thread on Tom’s hardware a user had an issue when they seemed to be hitting the power limit. An undervolt fixed their problems!