The joke about this power supply starts on the manufacturer website. As you can see there, all their models are deliberately overspec’ed. For example, the “YP620-AB” model is a “550 W” model, believe it or not. And even then it is stated that the main positive voltages cannot deliver more than 500 W together. This would mean that the other outputs (-5 V, -12 V and +5VSB) could deliver the remaining 50 W, right? But if you add things up you will notice that they can only deliver 21.1 W (1.5 W + 9.6 W + 10 W). What a joke.

If you take the 500 W model sold by Apevia (ATX-AS500W-BL), you will see that it has the same label as the Young Year YP-600-AB model, which is labeled by Young Year as a 500 W unit. But on Apevia’s website there is one interesting thing. Two, as a matter of fact. The first one is that contrary to Young Year’s website all the currents are labeled as “maximum”, with lower specs labeled as “normal”. These “normal” currents would be 20 A for the +3.3 V output (instead of 28 A), 24 A for the +5 V output (instead of 30 A) and 25 A for the +12 V output (instead of 34 A). Even then we think these numbers aren’t real, as we shall discuss in more details in a moment. The second thing we notice was this funny typo, where “tolerance” was written “torrance”.

The model we bought was labeled by Brazilian distributor Leadership as a 550 W model, and the crazy thing about it is that is impossible to find any model at Young Year’s website that has the same label as this unit. Even worse, as you can see on Figure 15, the label also lists the specs for two other models, 600 W and 700 W, and we can’t find at Young Year’s website any product with the same power specs. So we think Young Year will simply print whatever you pay them to print. Do you want a 900 W power supply? No problem, we will make the sticker for you!

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Figure 15: Power supply label.

As we saw on the previous page, the +3.3 V, +5 V and +12 V rectifiers used by this power supply can only deliver up to 30 A (99 W), 30 A (150 W) and 10 A (120 W), respectively. Keep in mind that these are the maximum currents and power specs for the rectifiers only, the maximum current/power the power supply is able to deliver will depend on the other components used, especially on the transformer, on the coils, on the electrolytic capacitors and even on the width of the printed circuit board traces.

The point is. NO YP-AB model can deliver what the manufacturer says. If you take the smallest model, YP-450-AB, which is officially a 350 W unit, its +12 V line is labeled as 15 A while the +12 V rectifier can only deliver 10 A!

The difference between the components used and the Leadership model we bought is outrageous, they labeled the +3.3 V, +5 V and +12 V outputs as capable of delivering 32 A, 34 A and 36 A, respectively, which is impossible using the components we found inside this unit. The most absurd difference is on the +12 V output (10 A/120 W vs. 36 A/432 W).

Some reader could point out that we are wrong as the maximum current of each rectifier is labeled under temperatures above 100º C and thus they could deliver a higher current when running at a lower temperature. This could make a little sense, however we’ve never seen a power supply where the rectifier maximum current is lower than the current printed on the label. Actually it is the contrary that normally happens: the rectifier maximum current is higher than the power supply labeled current – the double, in some cases.

The information that this is a 550 W (or any other power spec above 350 W) is a complete lie. Unfortunately we don’t have the required equipment to see the maximum power we could pull from this unit.

Just as an exercise, if we added up the maximum theoretical power for the three main positive voltages, we would have 369 W. Since +5 V and +3.3 V outputs are connected to the same transformer output, we cannot simply add these two powers, as one output limits the other. If we considered a combined power of 150 W (the maximum theoretical power for the +5 V output), we would have a maximum power of 270 W for the main positive voltages. But, like we said, the maximum amount of power a power supply can deliver is always lower than the maximum power its rectifiers can deliver – it can be even the half. So we wouldn’t be surprised if the main positive voltages could only deliver around 150 W.

Just a quick comparison for you to see how absurd is the discrepancy between this power supply real power and its labeled power, on Seventeam ST-420BKV, which is labeled as a 420 W unit, the +12 V maximum theoretical power is of 480 W (4x greater than the theoretical value for Young Year YP-AB), the +5 V maximum theoretical power is of  400 W (2.67x greater) and the +3.3 V maximum theoretical power is of 132 W (1,3x greater).