I got the ratings directly from Molex, (i.e. 14A/pin) the inventor & major manufacturer of the connector.
Stating ratings in amps is absolute, doesn't matter what the DC voltage is, up to 32VDC. Things change at higher DC voltages & any AC voltage.
Stating in watts is relative, because both volts & amps must be known.
For example: the standard Molex-type power connector with +5VDC & +12VDC & 2 Power Returns (incorrectly referred to as Grounds). The 5V pin would have a 70W rating and the 12V would have a 168W rating, but they are the same exact pin. Stating in Amps, the voltage is irrelevant (up to a point).
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"...The thermal design power (TDP)..., refers to the maximum amount of power the cooling system in a computer is required to dissipate. The TDP is typically not the most power the chip could ever draw..."
The terms power and energy are frequently confused. Power is the rate at which energy is generated or consumed and hence is measured in units (e.g. watts) that represent 'energy per unit time'.
TDP is a measure of heat dissipation, not electrical consumption. In a 100% resistive circuit, they would be equal. In this case, you could measure the heat rise in BTU/sec or calories/sec & convert to watts. Your electrical space heater or electrical water heater are examples. Transistor circuit are not 100% resistive; so, this is not the case, here.
The dynamic power consumed by a switching circuit is approximately proportional to the square of the voltage:
P = C V^2 f
(where C is capacitance, f is frequency and V is voltage).
The cpu does not use 12VDC directly, there are voltage converters external & internal to the cpu. Based on all this, you can't just divide TDP by 12 to get amps consumed.
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The CPU may not need the 4-pin connector at all, for minimal loading. You still have the 24-pin mobo connector supplying 12V. As motherboards required more power, this was not enough, so they added the 4-pin, then the 6-pin & 8-pin.
As for the 4-pin connector, assume it can supply 28A to the motherboard. How the motherboard supplies this to the components is an entirely different matter. You cannot pump 28A in by way of a single point, so they have 2. A margin of safety might be half, so in reality, 7A/pin. 100% (14A) does not go to the cpu.
Power (Voltage & current) is supplied to the PCB (Printed Circuit Board) power planes (copper layers inside the PCB). Power exits the plane by the way of vias (the little tiny holes) to the surface on which the component is soldered or in the case of a thru-hole component, inside the PCB. Amps are limited by the size of vias & thru holes & thickness of copper, which require multiple connection points for something like a PCI-e connector or the 3-terminal devices (regulators) supplying power to the CPU. You can see the amount of connections points to the CPU by looking at all the electrolytic capacitors. I cannot assume that all the +12V within the power plane is tied together, some manufacturers may use multiple isolated +12V power planes. This would be a reason for some motherboards functioning with the connector attached and others will not function at all.
By supplying multiple voltage connection points, you insure minimum voltage drop across those points without the use of voltage sensing techniques which would increase the cost of the psu. And it's not provided for in the Standard.
Multiple power planes insures that the motherboard gets all the power it needs for all the cards that get plugged in and any cpu installed. It won't work at all without all the required power plugs attached.
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In the OP's case, it may have been borderline for a long time & a condition was finally reached which pushed it over the edge & something degraded or failed. The adapter cable is cheap & more of a Science Experiment than a permanent solution; it's possible that it will correct all. What I don't understand, is why the expensive motherboard with cheap peripherals? Graphics cards aren't that expensive. The PSU is just the wrong one, a correct one is in order.
