How to optimize PLL voltage

Solution 1:

The PLL voltage setting determines the voltage fed to the CPU's phase locked loop section. The phase locked loop section generates the clock signals for different parts of the CPU that are clocked at different frequencies. It generates the main core clock, the video clock (if the CPU has a video controller), the memory controller clock, the bus clocks, and so on.

The PLL is designed to run at a voltage of 1.8V and exceeding 1.98V is dangerous. However, when overclocking, stability seems to be better for many people in the 1.5V to 1.7V range. The only way it would reduce temperature significantly was if it allowed you to drop the core voltage.

Solution 2:

As documented here, the VCCPLL should be 1.80V +/- 5% and is specified at a max of 1.5A, which means it draws a maximum power of 2.835W. Since this is such a very low number compared to the >77W (stock, yours is probably higher) that the whole CPU draws, it will not provide significant power usage reductions. Of course you can experiment, but even if you lower it to 1.5V, you have gained a whopping 0.585W advantage, which is probably not worth the instability it may cause. Try sticking to reducing Vcore as much as possible.