Load peaks and capping
Let’s first look at the flowing currents at the 12VHPWR. This time I’ll show the normal gaming mode. I deliberately chose a distribution to three single 6+2 pin cables on the adapter here, because it also shows a certain peculiarity in the interaction with the power supply. First, let’s take a look at the flowing currents during gaming and around 305 watts of power consumption. Measurements were taken at coarser 20-ms intervals, i.e. around 50 times per second, to simulate the load on the supervisor chip of the power supplies (shutdown). We see that ALL load peaks are brutally capped at 35 A at the latest.
Nevertheless, we still need to take a look at the voltages, or the product of voltage and current flow. I already wrote that I measured at three different power supply connectors, even though all three connectors meet again on the graphics card’s PCB (or in the adapter). What we can now see here as much clearer fluctuations and peaks is due to the partially overvolting power supply and thus the voltage and not the currents. This is due to technical reasons, but not a big deal.
In the Torture test, things look even better on the graphics card’s side. The card mercilessly cuts the currents already at around 29 amps, at maximum OC it is then 30 to 41 A. Apart from the drops, which are harmless and serve to protect the card, there are no abnormalities.
If you now add the voltage again, you will see a stronger ripple, which again results from the somewhat jittery operating voltage. However, in the power supply’s honor, it has to be said that this affects all current products of all manufacturers and is certainly hardly avoidable. Again, there is the comparison without and with OC.
Because I would like to know it however still completely exactly, I resolve the whole once still more highly and take 20 ms as total running time. The intervals of 10 microseconds can just be measured sensibly and we also see the voltage here as a pink curve, whose average value is 12 volts, but which nevertheless alternates somewhat within the permissible range.
If you then convert that to the power consumption in watts, you get this picture:
I also did the whole thing again for the Torture loop, where we get to admire the regular drops. First again the currents:
And then again total wattage:
Power supply recommendation
Now we come to the point that completely reduces the expected sensation of exploding power supplies to absurdity. Because even IF you hopelessly overpower the card, no one really needs ATX 3.0 power supplies over 750 watts unless the CPU eats more than 300 watts. This is really just a job creation measure for the struggling power supply industry and only satisfies the sick imagination of some standardization fetishists. You really have to put it so harshly. Well, the card doesn’t draw 320 watts at 12VHPWR even at full load, but at least almost. However, I could only achieve this load with Furmark, so the transients are only very minimal here because there are also hardly any load changes. Thus, you should always stay below 750 watts even together with the CPU.
This is also the reason for my power supply recommendation, which for the 320-Watt models of the GeForce RTX 4080 is that a modern 650-Watt Gold or Platinum power supply should be sufficient. With a full power limit of well over 355 watts and Furmark, a 750 watt model is sufficient if the power supply isn’t absolute junk.
- 1 - Introduction, unboxing and technical data
- 2 - Test system in the igor'sLAB MIFCOM-PC
- 3 - Teardown: PCB, components and cooler
- 4 - Gaming performance
- 5 - Power consumption and load balancing
- 6 - Peaks, transients and PSU recommendation
- 7 - Temperatures, clock rate, fan speed and noise
- 8 - Efficiency, summary and conclusion
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