TR2 XP550 NP (W0070, 430W)

I mentioned this model explaining the position of the XP480 in this article. The XP480 doesn’t have an official model number whereas the XP500 belongs to the TR2 series and has a model number of W0070. The TR2 series comprises inexpensive PSU models from Thermaltake that are not worthy of the PurePower brand.

The XP480 and X550 have a remote semblance. You can guess common design features, but the cooling fans are placed in a different way in the XP550. There are two of them here, but they are now located on the opposite sides of the case (that’s why you can’t see the second fan in the snapshot above).

The PSU is manufactured by HEC/Compucase.

Everything is easily recognizable on the inside, though. The internals of this PSU are the same as were installed in the XP480, except that the heatsinks are larger here (they don’t have to be adapted for the second fan that used to hang from above) and the input capacitors are now 680µF rather than 470µF. Otherwise the circuit design is identical. To all appearances, this is a version of the 300W HEC unit re-marked by Thermaltake as having 430W wattage. Here, the second fan may help the PSU a little – they had to make the heatsinks smaller in the XP480 to find place for the second fan, but the heatsinks are full size here and should cool the semiconductor elements better.

The PSU offers the following cables and connectors:

• A cable with a 20+4-pin ATX connector; 48cm long
• A cable with a 4-pin ATX12V connector; 49cm
• A cable with a 6-pin graphics card connector; 49cm
• Two cables with three Molex connectors and one floppy mini-plug on each; 48cm from the PSU case to the first connector and 10cm more to each next connector
• One cable with three Molex connectors; 48cm+10cm because the additional connectors are attached in parallel rather than in series
• A cable with two SATA power connectors; 48cm+10cm

There is again an abundance of Molex connectors for PATA drives, but a second SATA connector and a graphics card power connector have been added.

480W wattage is declared for this power supply, and there’s no mention of the peak output load on the label. The load currents aren’t much higher, though. The most important +12V line is now declared to provide a 1A higher current.

The cross-load characteristics of this PSU are similar to the XP480’s, which is logical since they have the same circuit design. The +12V voltage is stable, the +3.3V is very good, but the +5V voltage is a little higher than necessary. And once again I want to draw your attention to the rainbow patterns in the top right of the diagram where the PSU worked at about 380W – the +5V voltage is suddenly very low there.

I couldn’t measure the output voltage ripple for this PSU due to the same reason as with the XP480: half a hundred watts short of the declared maximum output power, at a load of about 380W, the PSU’s switching transistor overheat and burned down in the power supply. It was so hot that the insulating plastic spacer under the screw the transistor was fastened with melted.

The PSU has two 80mm fans connected to the same speed controller. So, their speeds coincide with a pretty high precision. The speed is adjusted in a linear manner, with a bend in the middle of the graph. The PSU is not silent – and you can’t expect a low-end model to be such – but it is quiet enough at everyday work as to provoke no complaints from most of users.

This PSU is more efficient than the XP480, but not too much – the graph touched the 80% line only once in the diagram. The power factor is low due to the lack of PFC and is about 0.65 on average. The PSU allows to install a passive PFC device and it is indeed installed in the W0069 model whose power factor should be higher at about 0.7-0.72.

So, like its predecessor, the XP550 isn’t true to the declared wattage. This is in fact an ATX12V 1.3-compliant 300W unit from HEC reinforced with a second fan. This may make it a 330W unit, but not better. The PSU just burns down at a load of 380W due to overheat of the switching transistor.

So, the W0070 can be viewed as a good low-end 300W power supply with accurate assembly, good parameters, and quiet operation… But on the other hand, Thermaltake put a label that reads “430W” on this product and this number has nothing to do with reality. This PSU cannot yield this output power for more than a couple of minutes. What’s the most disappointing thing, Thermaltake prices this PSU by the declared rather than real wattage and it costs now $45 or even more (unlike the XP480, the XP550 comes to retail shops apart from system cases). I think it’s unfair to put so high a price on a mediocre power supply built to comply with an obsolete standard.