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- Thread starter Kol12
- Start date

Martin said:Yes, that should be the current read from VRM. I think your PSU should have multiple rails.

Are you saying that reading is like a total current draw from the PSU? I have just one 12V rail, Seasonic X-750 - http://www2.seasonic.com/product/x-750/

Not sure if I explained it well

The reading you're getting in HWiNFO (50 Amps or 81 Amps) is at the CPU voltage, which is somewhere around 1.0 to 1.3 Volts. This equals the 57 (or 98) Watts HWiNFO shows. This value is not directly related to the output power of your PSU, because it's at a much lower voltage. Between the PSU and CPU there are voltage regulator modules (VRM) that convert the PSU's 12 V to a lower voltage that the CPU needs; IIRC it's higher than Vcore, something around 3.x volts or something, but I digress.

The power drawn from the wall is completely different from both of the above, and it has nothing to do with the power rating of your PSU. It has something to do with the efficiency of your PSU at a given AC voltage (110 vs. 230 Volts). That's why the efficiency rating can be slightly different for the different AC voltages.

Regards

Dalai

Kol12 said:The CPU alone drawing 50-80 Amps is the whole of my PSU's 750W and more.

No, it's not. The 750 Watt of your PSU is the maximum limit of your PSU on all rails combined. Each rail has its own power limit, which is 62 Amps in case of the 12 V rail. The other rails can be ignored in regards to the CPU (12 V is the only one that matters).

A CPU can draw 100 Amps (just a random number, not necessarily related to reality), and it doesn't go over the 62 Amps limit of your PSU. Why? Because 100 Amps at 1.2 Volts is MUCH LESS power drawn than your PSU can deliver: 62 Amps at 12 Volts. Let's calculate the example in full: 100 Amps at 1.2 Volts equals 120 Watts. 62 Amps at 12 Volts equals 744 Watts. 120 is much smaller than 744, less than 20 percent.

I know there is something I'm missing I just haven't got it yet. :/

Power (Watt) is the product of current and voltage, or expressed mathematically, Power = Current * Voltage. You always have to take both voltage and current into account when talking/thinking about power.

Regards

Dalai

Kol12 said:@Dalai I'm sure what you say is correct it is just very confusing. :-/ Obviously I need to do some electrical study to better understand this.

Try this one, input 1.3V and 60A, then click calculate:

https://www.rapidtables.com/calc/electric/watt-volt-amp-calculator.html

Next, clear all boxes with reset button and input wattage you got from previous calculation, then input 12V and click calculate

Next you can then continue to do same with whatever is your wall voltage, that probably gives you better picture of what is relation of amps and volts.

Code:

`Power = Voltage * Amperage`

If you change one of the values, you need to change the other values, too. Let's say, you have these numbers:

Code:

`744 Watts = 12 Volts * 62 Amps`

If you change the Voltage, you must change the Amperage as well, so that the equation is still correct, and the Power stays the same. Let's change the Voltage to 1.2 Volts (VCore), which is what the VRM's on any motherboard do. What needs to be done to keep the equation valid? The Amperage needs to be multiplied by 10 because the Voltage was divided by 10. The result is this:

Code:

`744 Watts = 1.2 Volts * 620 Amps`

It's also possible to change the Wattage on the left side of the equation:

Code:

`74.4 Watts = 1.2 Volts * 62 Amps`

In short: If one value is raised another value must be lowered to keep the equation valid. That's why 100 Amps at 1.2 Volts are a completely different thing than 100 Amps at 12 Volts - the resulting power is 10 times higher in case of the latter.

Regards

Dalai