Where to start. Multiple pins supplying power to a die isn't done because they can't clonk a pair of big connectors in the middle. The resistance within the die would cause different ground levels and voltage drops if supplied at only one physical ___location. The PCB has much more space for "thick" copper traces (complete ground plane) and buffer caps to supply a stable voltage across the entire die.
Second, CPUs have a dedicated 12V rail on the MB since quite some time. It's plugged in right near the voltage regulators of the CPU.
Third, a GPU die also has multiple power rails and distribution over the die as CPUs. Given the insane power requirements and transistor count, they likely have even more. The same is true for other power hungry ICs, for example high-speed DSPs, FPGAs, image sensors and so on.
Fourth, PCI/PCIe can't carry hundredths of watts, it would not be cost effective to kit out PCs with heavy duty connectors and thick main board traces just because one or two slots may one day be used for a space heater. Thus another dedicated rail from the PSU.
Second, CPUs have a dedicated 12V rail on the MB since quite some time. It's plugged in right near the voltage regulators of the CPU.
Third, a GPU die also has multiple power rails and distribution over the die as CPUs. Given the insane power requirements and transistor count, they likely have even more. The same is true for other power hungry ICs, for example high-speed DSPs, FPGAs, image sensors and so on.
Fourth, PCI/PCIe can't carry hundredths of watts, it would not be cost effective to kit out PCs with heavy duty connectors and thick main board traces just because one or two slots may one day be used for a space heater. Thus another dedicated rail from the PSU.