Load peaks and capping
Let’s first take a look at the flowing currents. Measurements were taken at rough 20 ms intervals, i.e. around 50 times per second, in order to simulate the load on the supervisor chip of the power supply units (switch-off). We can see that ALL load peaks are capped at 39 A at the latest, which is just fine. The RX 7900XT from AMD generated similar peaks of up to 39 amps in places!
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 somehow on the graphics card board. What we can now see here as much clearer fluctuations and peaks is due to the power supply unit overvolting a little in places and therefore to the voltage and not the currents. This is due to technical reasons, but is not a problem. However, we can also see that the few peaks up to and over 500 watts are not caused by the flowing current (graphics card), but actually result from the power supply!
The Torture test is hardly any different, even if you can see the lower peak values and, above all, the drops. The average, on the other hand, actually rises slightly.
If we now add the voltage to the equation, we see a stronger ripple, which in turn results from the somewhat jittery operating voltage. However, to the power supply’s credit, it must also be said that this affects all current products from all manufacturers and can hardly be avoided.
But because I still want to know exactly, I resolve the whole thing even higher and take 20 ms as the total runtime. The intervals of 10 microseconds can still be measured reasonably and we can also see the voltage here as a gray curve, the average value of which is just over 12 volts, but which nevertheless still alternates a little within the permissible range.
If you then convert this to the power consumption in watts, you get this picture:
I did the same thing again for the Torture Loop, where we can admire the regular drops. First of all, the currents again, but with lots of strange, sporadically recurring drops on every climb. This looks like a violent hiccup before the power is really throttled back shortly afterwards.
And then the total wattage again:
Power supply recommendation
Now we come to the point that makes the expected sensation of exploding power supplies completely absurd. Even IF the card is hopelessly overpowered, nobody actually needs ATX 3.0 power supplies over 1000 watts for such cards, unless the CPU consumes more than 400 watts. This is really a pure job creation measure for the starving power supply industry and only satisfies the sick imagination of some standardization fetishists. You really have to put it that harshly. So you should always stay below 600 to 700 watts, even together with the CPU, if you count up to 10 ms. Because that’s what the power supply units still “see”
My power supply recommendation for the Sapphire Radeon RX 7900 GRE 16 GB is that a modern 650-watt gold or platinum power supply should get you there quite safely. If you want to overclock, you should plan for 50 to 100 watts more, which is especially true for the board partner cards.
- 1 - Introduction, technical data and technology
- 2 - Test s4etup and methods
- 3 - Teardown: PCB and components
- 4 - Teardown: cooler and cleaning tips
- 5 - Teardown: material analysis
- 6 - Gaming-Performance Full-HD (1920 x 1080)
- 7 - Gaming-Performance WQHD (2560 x 1440)
- 8 - Gaming-Performance Ultra-HD (3840 x 2160)
- 9 - Gaming-Performance DLSS / FSR (3840 x 2160)
- 10 - Gaming-Performance FSR3 Frame Generation (3840 x 2160)
- 11 - Latenzen
- 12 - Power consumption and balancing
- 13 - Transients and PSU recommendation
- 14 - Temperatures, IR analysis and clock rate / OC
- 15 - Fan curves, noise and audio sample
- 16 - Summary and conclusion
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