PurePower TWV500W-AP (W0057, 500W)

The TWV abbreviation in the name of this power supply stands for Total Watt Viewer, i.e. indication of the amount of power consumed. What’s curious, the detachable cables of this PSU seem to be a more interesting feature than the power indicator (yes, it looks pretty but has no practical purpose), yet this is not shown in the model name. Moreover, this PSU has independent voltage regulation, which is not emphasized in any way in its characteristics. Thermaltake officially declares this feature for its newer ToughPower series, but not for PurePower.

The PSU has a black matte case and is cooled with one 12cm fan (highlighted with blue LEDs). The actual developer and manufacturer of the unit is Sirtec.

Prominent inside the PSU case are the composite heatsinks which are thick aluminum bars with slanting ribs riveted to their sides. The next thing that may catch your eyes is the three toroidal chokes on the PSU output instead of the usual two. This means independent voltage regulation. There are usually two chokes in ordinary power supplies. One is necessary for group voltage regulation (it helps reduce the interdependence of the output voltages), and the other in the so-called magnetic amplifier circuit regulates the +3.3V voltage (group regulation isn’t sufficient for it). This solution simplifies the overall design of the power supply, but makes the +5V and +12V voltages dependent on each other: the PSU’s regulator aims at a certain arithmetic mean between them.

The addition of one more choke solves the problem altogether: the PSU’s main regulator is now only responsible for the +12V voltage, instead of trying to find the optimal values of the +12V and +5V voltages simultaneously. In an ordinary unit this would result in poor stability of the +5V voltage (the output voltage on this rail would depend greatly not only on its own load, but also on the load on the +12V rail), but there is an additional regulator on the +5V in this power supply, the same in fact as on the +3.3V rail. It’s only the low-power -12V rail that is left unregulated, but the low currents make it possible to put an integrated linear regulator like the LM7912 on it. So in the end the power supply becomes more expensive (the extra choke costs some money by itself and also makes the assembly of the PSU more difficult by occupying quite a lot of room in its case), but its output voltages become much more stable. I don’t claim this is a crucial advantage because a majority of high-quality power supplies yield stable enough voltages throughout all the range of loads, but it’s good to have this extra regulation anyway. Of course, if the circuit is assembled carefully and works well.

The non-detachable cables on the PSU have connectors for the manual fan speed controller and for the indicator of consumed power. The rest of the cables are detachable, although I don’t quite understand why the mainboard and CPU power cables are made such. You always have to use them while the extra pair of contacts reduces the overall reliability of a circuit.

The longest connector has 24 pins, it’s for the mainboard power cable. Next to it, there are two 6-pin connectors to power your graphics cards, and an 8-pin one for the CPU. Then, there are five 4-pin connectors for PATA drives – these have only two voltages, +5V and +12V. The cables for SATA drives are complete, with +3.3V voltage besides the rest. The SATA power cables are attached to the PSU with two connectors, with a main 4-pin one and a separate 2-pin one (there are two such sockets below) through which the +3.3V voltage is supplied.

The box with the PSU contains:

• A mainboard power cable with a 20+4-pin connector, 50cm long
• A CPU power cable with a 4-pin ATX12V connector, 50cm long
• One cable with three Molex connectors, 50cm to the first connector and 20cm more to each next one
• Two cables with three Molex plugs and one floppy mini-plug on each, 50cm to the first connector and 20cm more to each next one
• Two cables with 6-pin graphics card power connectors, 50cm
• Two cables with two SATA power connectors, 50cm to the first connector and 20cm more to each next one

Besides the cables, there is a module to control the speeds of two fans and to display the amount of power the PSU consumes. This module is inserted into a 3.5” bay of your system case and it resembles the module included with the W0023. Unlike Zalman’s controllers, for example, this one is only meant for work with fans that have a dedicated connector for speed management. To put it plain, it only supports fans from Thermaltake, and one such fan is included with the power supply to make your life easier. It is a 12cm TT-1225A (Everflow R121225SU, 2900rpm) without highlighting. I tried it out and found that its speed was varying from 1250 to 2850rpm. This is quite a high speed for a quiet computer. Enthusiasts usually slow the fans of their systems down to 800-900rpm. At this speed the fans are practically silent but produce enough airflow to cool the system case. At speeds above 2000rpm any 12cm fan is noisy just because the strong airflow they create produces a hissing sound. So, if you want to assemble a really quiet computer, you are unlikely to be satisfied with the speed controller included with the W0057. It’s impossible to make the fan you receive with it quiet (this is the most powerful model in Everflow’s 12cm fan line-up), while replacing it with another fan is going to be problematic because the controller supports only a few select fan models.

The 7-segment display of the module shows you the amount of power consumed. Such devices generally lack precision, but this sample did quite well. In a range of loads from 50 to 300W its showings were indeed accurate. At higher loads the indicator would show a 30-40W higher value, while at lower loads its showing would drop not to 0, but to 10W.