The CPU current reading is the current leaving the motherboard VRM and going into the CPU's FIVR at the VINPUT.

Your VINPUT is not +12v. It's probably in the ballpark of 1.9v. 1.9*85 = 161.5. 161.5 (rough guess on CPU power consumption at whatever load that reading is from) / 12 (voltage going into the board VRM * 1.1 (assuming ~90% VRM efficiency, which is a lowball) = 14.8 amps from the +12v rail on the PSU.

Your PSU is more than sufficient to power all the hardware in your system, even under worst case loads.

 

You may be confusing watts and amps. When I pulled up HWinfo, I can't find an amp reading anywhere on it. The CPU readings I see are either in volts or watts.

Watts = volt times amps so a 12V rail times 85 amps = 1020 available watts. More than enough for your CPU and GPUs.

 

Quote:

Originally Posted by Tom B

You may be confusing watts and amps. When I pulled up HWinfo, I can't find an amp reading anywhere on it. The CPU readings I see are either in volts or watts.

Watts = volt times amps so a 12V rail times 85 amps = 1020 available watts. More than enough for your CPU and GPUs.

 

Here's a screen shot of HWiNFO. You can see the value under the Asus EC sensor section for CPU Current, which in this particular screen shot has max value of 83A; however, I've seen it at 86A, but the PSU max 12V rail A is 85A.

 

Don't you understand that the CPU doesn't run at 12V? Average 5930K uses 1.1V-1.3V. 1.3 x 85 = 110 watts.

 

Oh yeah you're right the 24 pin ATX connector isn't all 12V it's a mix of all the voltages. The additional 8 and 4 pin are all 12V though. So that 83A value may be accurate, but it's a total A from multiple rails. Is that the point you're trying to make?

 

Quote:

Originally Posted by james41382

Here's a screen shot of HWiNFO. You can see the value under the Asus EC sensor section for CPU Current, which in this particular screen shot has max value of 83A; however, I've seen it at 86A, but the PSU max 12V rail A is 85A.

Again, this is VINPUT, not +12v.

Your CPU is only pulling ~15A +12v.
Quote:

Originally Posted by Cyclops

Don't you understand that the CPU doesn't run at 12V? Average 5930K uses 1.1V-1.3V. 1.3 x 85 = 110 watts.

VINPUT will be 1.8-2.0v on most X99 systems and thats what current is usually measured, not vcore.
Quote:

Originally Posted by james41382

Oh yeah you're right the 24 pin ATX connector isn't all 12V it's a mix of all the voltages. The additional 8 and 4 pin are all 12V though. So that 83A value may be accurate, but it's a total A from multiple rails. Is that the point you're trying to make?

No.

 

I understand how electricity works from Physics. In particular the relationship between power, currrent and voltage, where W = IV. For example, the max value for CPU Power is ~158W while the max value for CPU Current is 83A. So from the equation we verify that the VCCIN voltage is ~1.9V as expected because that is what it's set to in the UEFI.

I still don't understand where the 83A comes from though. I know the 24 pin ATX connector gets power from multiple rails and I know that the additional CPU power connector (EPS) is all 12V leads. Are you trying to tell me that although the additional power connector comes from the 12V rail it's not used by the CPU?

 

The ATX 24-pin connector doesn't supply the CPU on most modern boards/platforms. Even if it did, the rails wouldn't be combined.

Power goes from your PSU's +12v rail, through the 8-pin ATX/EPS +12v connector, into your motherboard's VRM. From here, it's converted to whatever your CPU's VINPUT is, then sent to your CPU.

The 83A is what leaves the motherboard VRM and goes to the CPU at a voltage equal to the VINPUT.

That 158w @ 83A peak power reading means your actual vinput is very close to 1.9v and also means that somewhat more than 13.2A (the VRM isn't 100% efficient at conversion) is being drawn from the PSU's +12v.

So, like I said earlier, ~15A is a good estimate of the +12v amperage used by your CPU.

 

Quote:

Originally Posted by james41382

I understand how electricity works from Physics. In particular the relationship between power, currrent and voltage, where W = IV. For example, the max value for CPU Power is ~158W while the max value for CPU Current is 83A. So from the equation we verify that the VCCIN voltage is ~1.9V as expected because that is what it's set to in the UEFI.

I still don't understand where the 83A comes from though. I know the 24 pin ATX connector gets power from multiple rails and I know that the additional CPU power connector (EPS) is all 12V leads. Are you trying to tell me that although the additional power connector comes from the 12V rail it's not used by the CPU?

83A is the measurement of the current on the input side of the CPU, not the current being drawn over the EPS cable from the PSU. You have to convert everything to power for it to make sense.

CPU draw = 83A * 1.9V = 158W
PSU draw = 158W = 12V * 13.2A

 

Quote:

Originally Posted by james41382

I understand how electricity works from Physics. In particular the relationship between power, currrent and voltage, where W = IV. For example, the max value for CPU Power is ~158W while the max value for CPU Current is 83A. So from the equation we verify that the VCCIN voltage is ~1.9V as expected because that is what it's set to in the UEFI.

I still don't understand where the 83A comes from though. I know the 24 pin ATX connector gets power from multiple rails and I know that the additional CPU power connector (EPS) is all 12V leads. Are you trying to tell me that although the additional power connector comes from the 12V rail it's not used by the CPU?

W/V=I

158/1.9= 83.157894736842105263157894736842

your vrms are regulating the 12v to 1.9v, that is what is throwing you off.

to see that load from the PSU:

158/12= 13.166666666666666666666666666667

seriously, if your cpu was using ~85amps off the 12v your system would be shutting down w/2 gpus.

ooops just repeated kl6mk6 post. sorry had the reply open for awhile watching a video . .

 

Just to reiterate what others have said, that 85 amp reading you're seeing is not what's being drawn from the power supply, it's what's being drawn from the motherboard VRMs, which are kind of like a transformer. They take the (relatively) high voltage (12v), low amp (13-15A as calculated by the others) input from the PSU, and convert it to low voltage (1.8-1.9V), high amp (85A) to feed the CPU. You could probably power that system with as little as a good quality efficient 650-750 watt PSU in reality.

 

Thanks for the explanation everyone. It makes sense to me now. The voltage from the PSU gets converted from 12V to CPU input voltage. So the reading on that sensor is the current going in to the CPU, but it's not equal to the current coming from the PSU. Well done.