So PPT/TDC and EDC together define the TDP of a processor. A 105W TDP processor has default settings of 142W/95A/and 140A respectively. While a 65W processor is 88W/60A/90A respectively.
PPT stands for package power tracking. This is the maximum allowed work in wattage the processor is allowed to do.
TDC is the thermal design current. And is the maximum current in amps the CPU is allowed to sustain over the motherboard VRMs.
EDC is the electric design current. This is the absolute maximum current the CPU can use even in a short term spiked scenario.
When your processor boosts, it will attempt to reach Fmax (maximum frequency) within a fixed voltage envelop. However, it can be stopped before Fmax if it hits the max allowed temperature, or any of the other boundaries listed above.
The function of those settings is to give you an idea of the kind of cooler you'd need to run the processor. A processor allowed to do 142W of work on 95A will need a cooler that can dissipate 105W etc.
When you engaged precision boost overdrive, you can set the PPT/TDC and EDC limits to "motherboard" which places them at values so high that they essentially are no longer constraints. This is "safe" as the processor will still not exceed the voltage constraints or the maximum allowed temperature. Effectively, with PBO enabled, Fmax, voltage and temperature become the only bounds. Of course, most users don't like being at max temp all the time, so they set these bounds to something more reasonable. My 5950X is liquid cooled, so I set it to 203W/140A/207A. This is effectively a 150W TDP, but it is also the setting at which my CPU hits 70C on and all core load. I am completely PPT bound when running and all core load, which means the processor would gain more if I increased the limit, but at the expense of more heat. The extra performance gained going up to 85C doesn't really justify the heat generated
The Ryzen 9 7950X is a great example of that. It has a default TDP of 170W or 225W/160A/220A. But if you run it as a 105W processor (142/95/140) it loses less than 10% of its multicore performance. So those CPUs have been pushed way passed the efficiency curve right out of the box, and you can save big on temps and power draw by using the PPT/TDC/EDC settings.
Now, PPT/TDC/EDC usually don't affect lightly threaded workloads at all. If you are running a single thread or just a few, there won't be nearly enough wattage or current in play. Where they do matter is in all core boosts. Take a Ryzen 7 5800X, within the default TDP you will be able to hit a certain clock speed when all 8 cores are boosting. Now, the Ryzen 9 5950X will hit a much lower clockspeed. It has the same default TDP of 105W, but it takes alot more current and generates more wattage boosting 16 cores vs 8. So you are going to hit 142W and/or 95A at a lower clockspeed.
So the more cores you have, the more you will benefit from a raised PPT/TDC provided your cooler can keep up with the extra heat generated.
So like I said, for single threaded overclocking, those cut points don't matter at all, because you typically aren't reaching them even at default. You are usually just bound by the max voltage and Fmax. If you processor hits Fmax, it stops boosting. Or, if it hits the max allowed voltage. So curve optimizer allows you to shave off some voltage from the boosting algorithm. The processor will then attempt to boost to a certain clockspeed using less voltage than in normally would. As long as the voltage is still sufficient to maintain the clockspeed, the system will be stable. This generates some additional headroom to boost a bit further within the allowed voltage envelope.
You can also extend the voltage range by increasing the scalar. But increasing in much past 2X isn't really recommended if you want to make sure you maintain the life of your silicon.
