Sapphire Radeon RX 7900 XT 20GB Review – The cheaper variant isn’t the worst!

Load peaks and capping

First, let’s take a look at the flowing streams. 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 37 A at the latest, which is fine. AMD’s RX 7900XT even produced higher 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 here at three different power supply connections, even if all three connections meet again somehow at the end on the board of the graphics card. 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 few peaks up to almost 500 watts is not due to the flowing current (graphics card), but actually results from the power supply!

The Torture test is hardly any different, even if you can see the lower peak values and especially the drops. The average, on the other hand, is actually rising slightly.

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 of all, the streams again, but in each rise still have plenty of peculiar, sporadic drops. This looks like a violent hiccup before the power is really throttled again shortly afterwards.

For comparison, here is the GeForce RTX 4070 Ti, which has a similar load management, but varies in the course of the increases:

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. Thus, you should always stay below 600 to 700 watts even together with the CPU, if you count up to 10 ms. Because it is what the power supplies still “see”

This is also the reason for my power supply recommendation, which for the Sapphire Radeon RX 7900 XT 20GB is that you should be able to get by with a modern 650-Watt Gold or Platinum power supply. If you want to overclock, you should add another 50 to 100 watts, which is especially true for the board partner cards.