Without getting super technical as it is outside the scope of this article, additional phases ‘smooth’ out the power distribution to the processor, which is important for the purposes of stability, both as core counts scale upwards and higher frequencies are reached. So with a multi-phase design, the ‘load’ of power is smoother, and you can think of it (if you want an analogy) of a half-life for medication. You take a pill and then the half-life for the pill could be 4 hours, so after 4 hours the pill only has 50 percent of the drug left in your system.
credit –
Voltage Regulator Module (VRM) - WikiChip
So if you’re taking antibiotics, you take the pills evenly spaced out to consistently keep the medication in your body… phases work similarly here, only instead of antibiotics, you’re feeding the processor power. The trick is to overlap phases with a slight offset, so that as one phase ‘drops’ its voltage to the CPU the next phase does its thing. You can see the above illustration on how the it creates a smoother line, compared to how each of the peaks (for example, phase 1) would look if it worked in isolation.