Load peaks and capping
Let’s first look at the flowing currents at the 12VHPWR. First, let’s take a look at the flowing currents during gaming and just under 300 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 capped at 35 A at the latest, whereby you don’t find the exact brake that the GeForce 4090 can use. This is pretty much up to 380 watts on average per interval (we’ll analyze the peaks in a moment). So that’s all the power supply “sees”! Nevertheless, this is still exemplary and also completely harmless.
But 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 partial slightly overvolting power supply and thus the voltage and not the currents. This is due to technical reasons, but not a big deal. However, we also see that the one peak at around 450 watts is not due to the current flowing (graphics card), but actually results from the power supply! Of course, reviewers should also take this into account.
In the Torture test, things look even better on the graphics card’s side. The card mercilessly caps the currents at around 29 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.
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 gray curve, whose average value is just over 12 volts, but which nevertheless still 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 flows, but in each rise still has a peculiar recurring drop. This looks like a small hiccup before the power is really throttled again shortly afterwards.
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. Even IF you hopelessly overpower the card, 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 320 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 in relation here, because there are also hardly any load changes. Thus, you should always stay below 600 to 700 watts even together with the CPU.
This is also the reason for my power supply recommendation, which for the OC models of the GeForce RTX 4080 is that you should be able to get by with a modern 650 or 750 Watt Gold or Platinum power supply. With a full power limit of up to 400 watts and Furmark, an 750 watt model is also sufficient if the power supply isn’t absolute junk. Even though my list is short and I couldn’t test each power supply for more than 1 hour, I simply ran through what was still unassembled on the shelf in the lab and lasted.
| be quiet! |
Straight Power 11 650 Watt Gold |
| Corsair |
RM 650 Gold 650 Watt |
- 1 - Introduction, technical data and technology
- 2 - Test system and the igor'sLAB MIFCOM-PC
- 3 - Teardown: PCB, components and cooler
- 4 - Gaming performance WQHD (2560 x 1440 Pixels)
- 5 - Gaming performance UHD (3840 x 2160 Pixels)
- 6 - Gaming performance UHD + DLSS/FSR/XeSS (3840 x 2160 Pixels)
- 7 - DLSS 3.0 and the longest benchmark bars
- 8 - NVIDIA Reflex and latencies
- 9 - Workstation performance
- 10 - Power consumption, load levels and standards
- 11 - Transients and PSU recommendation
- 12 - Temperatures, clock rates, OC, fans and noise
- 13 - Summary and conclusion
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