Final answer:
Overclocking is the performance-enhancing technique that voids most manufacturers' warranties.
Step-by-step explanation:
The performance-enhancing technique that usually voids most manufacturers' warranties is overclocking.
Overclocking refers to the process of increasing the clock speed of a computer component beyond its default settings to enhance its performance.
However, overclocking can put additional stress on the component, leading to higher temperatures and potential stability issues, which is why most manufacturers void warranties if a component has been overclocked.