Load peaks and capping
Let’s first look at the flowing currents at the 12VHPWR. I deliberately chose a distribution to four single 6+2 pin cables on the CableMod adapter here, because it still shows some peculiarity in the interaction with the power supply. First, let’s take a look at the flowing currents during gaming and around 376 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 42 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 connections, even though all three connections 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 caps the currents at around 37 amps already. Apart from the drops, which are harmless and serve to protect the card, there are no noticeable features.
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
We now come to the point that completely reduces the expected sensation of exploding power supplies along with the ATX 3.0 blubber to absurdity. Even IF you were to hopelessly overpower the card (which isn’t even possible here), no one really needs ATX 3.0 power supplies over 1000 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 460 watts at 12VHPWR even at full load, but almost. I could also 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 850 watts even together with the CPU.
This is also the reason for my power supply recommendation, which for the 450-Watt models of the GeForce RTX 4090 is that you should be able to get by with a modern 850-Watt Gold or Platinum power supply if the power supply is not absolute junk.
- 1 - Introduction, technical data and technology
- 2 - Test System and the igor'sLAB MIFCOM-PC
- 3 - Teardown: PCB and cooler
- 4 - Gaming Performance
- 5 - Power Consumption and load balancing
- 6 - Transients and PSU recommendation
- 7 - Temperatures, clock rates, fans and noise
- 8 - Efficiency. summary and conclusion
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