Power Analysis

On Figure 27 you can see Tagan TurboJet TG1100-U95 label stating all its power specs.

click to enlarge
Figure 27: Power supply label.

As you can see this power supply has four virtual +12 V rails (inside the power supply all these rails are connected to the single +12 V line this power supply has). Unfortunately all manufacturers seem to be doing like this to match the ATX12V 2.x and EPS12V specifications, which require the power supply to have separated +12V rails.

From the previous page we came with some maximum theoretical numbers for the +12V output (2,880 W), +5 V (400 W) and +3.3 V (264 W).

As we mentioned earlier the maximum current/power each line can really deliver will depend on other components, especially the transformer, the coil, the capacitor, the wire gauge and even the width of the printed circuit board traces used.

For the +12 V output Tagan stated 20 A for each one of the power supply four virtual rails – Enermax states 17 A for each +12 V rail on its Galaxy 1000 W, however Galaxy has five rails. This would give a 240 W maximum per rail or 960 W maximum total – the number labeled by Tagan.

For the + 5 V output Tagan stated a 28 A maximum current (Galaxy 1000 W is labeled as 30 A), which translates to 140 W, while for the +3.3 V output the manufacturer also stated a 28 A maximum current (Galaxy 1000 W is labeled as 30 A), or 92.4 W. On the label, however, Tagan says that the combined power of +3.3 V and +5 V outputs is of 180 W, which is rather strange, as this two outputs use two separated circuits (they use the same switching section, though).

All positive outputs are labeled with a current well below the maximum current each rectifier can deliver, but as we mentioned several times, the maximum current/power will depend on other components, as all rectifiers are overspec’ed.

Unfortunately we don’t have the necessary equipment to make a true power supply review; we would need to create a real 1,100 W load with a load tester to check if this power supply could deliver its labeled power or not. As mentioned, our friends at Planet3Dnow.de have one and their Tagan TG1100-U95 burned when they tried to pull more than 768 W @ 25º C on the +12 V lines.

Also, as a final note, Tagan doesn’t specify the temperature under which the power supply is rated. Usually when no temperature is stated, the manufacturers assume 25º C, which is a temperature far below the power supply real working temperature. Keep in mind that the maximum power a power supply can deliver drops as its internal temperature increases. Here it is important to notice that Galaxy 1000 W from Enermax is rated at 50º C and also according to our friends at Planet3Dnow.de, it can really deliver its announced power.

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