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Zalman ZM400A-APF 400watt PSU |
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Written by Mikhail Ivanenkov
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Monday, 18 June 2007 |
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Page 2 of 3
The available connectors are as follows: six 4-pin molex, one floppy, one ATX, one 12V, and one AUX. Length is what I would call ideal for most systems. The wires are longer than those found on cheaper models, but not as long as anything from Antec or Enermax, so cable clutter in mid tower systems is minimized. As you can see, the supplied velcro straps do their share as well. What's unique about all this is the somewhat different arrangement of the molex connectors.
While most power supplies will have two per cable (and a separate molex with one or two floppy connectors), Zalman does things their way. Three of the molex connectors are on their own line. One has a single floppy connector attached (who needs two these days anyway?). The fifth and sixth are daisy chained. This not only allows for extra versatility, but keeps power loss to a minimum. This way you can keep important devices on their own channel (such as a master hard drive) without having to connect fans, lights and other drives on the same line (all of which causes instability).
The 3.3v and 5v rails have a combined rating of 235watts (above average for a 400watt PSU) and another 180watts on the 12v. The 15A rating for the latter could have been a bit higher, but it's not a major concern. Aside from some cautions and specs, the sticker also lists some of the more prevalent features of the power supply, such as the previously discussed CNPS fan control, active PFC and respectable efficiency.
The implementation of active PFC (Power Factor Correction) means a higher power factor (94% at full load, up from 75%) and less harmonic resonance. Active PFC uses active elements such as IC, FET and diodes to create a PFC circuit, whereas passive PFC uses passive elements (as the name implies) such as an iron core inductor. Although the passive method is more cost efficient, the power factor is significantly lower and harmonics are greater and harder to control, leading to higher levels of EMI. Another advantage of active PFC is that it can accept a full range (90-260v) of AC input, so no 115/230v switch is necessary (notice the sticker between the on/off switch and the plug).
Under the hood is a slew of circuits, wires, heatsinks, and other electrical parts. I'm being honest when I say that the sinks on the ZM400A are the largest I've seen in any power supply. Not only do they have fins on the rising section of the sink, but once they reach the top of the PSU they have a secondary section forming a T shape. Since the majority of new power supplies include dual fans (one belly mounted), they don't have room for larger sinks. Whether it's more effective to have more massive heatsinks or a second fan is something I leave up to the engineers, but in my time with Zalman's offering I'd have to say their approach works quite well.
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Last Updated ( Monday, 18 June 2007 )
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