Yeah, its pretty simple and frightening, If you start off with a big power supply you don't generate the voltage you intend to use If its very low, like CPU/GPU because a. you would require massive cables (even a stock CPU) pulls 50~100 Amps
b. you would have a massive problem with voltage drop/variations due to the conductor varying resistance due to the heating effect of the current.
So we feed the cards 12volts and it's locally regulated down to the core voltage, we can even send a sample of that core voltage back to those regulators so they can constantly vary their output so the core sees a nice constant voltage.
So once at that core that voltage is low but the current is massive.
I hate you

My head started to implode after all the reading yesterday,
completely forgot about dc/dc converters and the likes
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