As computer systems have become faster, they have required more power and more cooling. The result of this is systems that have a lot of heat to dissipate and noise from the myriad of cooling fans. Zalman was one of the first companies to really start pushing products that helped reduce the heat within modern PCs while trying to keep the noise levels down. This primarily comes from their line of cooling products, but they also produce other components such as power supplies.

The Power Supply

The Zalman ZM400-APS power supply is a 400W low-noise unit that should provide sufficient power for most desktop computer systems. The primary focus for reducing noise generated by the unit is the inclusion of a single 80mm fan that is variable speed depending upon the temperature within the unit. The Active PFC circuitry improves the units overall power efficiency between 74 and 94% depending upon the load.

Contents of ZM400B-APS Power Supply Box

The unit comes with a fair number of connectors. It includes the standard ATX power connectors, ATX +12V 4-pin connector, an Auxiliary power connector, seven 4-pin Molex connectors, two 4-pin floppy connectors and two Serial-ATA power connectors. It also includes a Multi-Connector that attaches to a specific 4-pin Molex connector that can supply two 5v and two 12v fan connectors. The unit does lack a fan speed wire header for a motherboard, so the system BIOS cannot monitor the power supply fan speed.

Zalman Multi-Connector

The wiring is long enough for it to be placed inside of a full size tower case. This is where one of the biggest disadvantages of the ZM400-APS comes in. Most units use a mesh wrap to keep the primary ATX power connector and its wire bundle under control. The Zalman unit forgoes this in favor of a few tie wraps that can make for a very messy installation. They have included two velcro cable ties in the package that can be used to keep the wires under control.

Power Specifications

Below are the power specifications on the label for the ZM400B-APS power supply:

Based upon the specification table, the 3.3v and 5v lines share a common circuitry set or power rail. This is evident because the combined voltage times amps for the 3.3v and 5v results in 292W of total power consumption compared to the rated 235W for the two lines. Of course with most modern systems, the 12v line is the most important as this is what drives power to the CPU, drives and even some of the most recent video cards. It has a solid 18A capacity that should power peripheral intensive desktops.

Testing

For the purpose of this review, the Zalman ZM400B-APS power supply is going to be compared to the Antec True Power 380W that comes supplied with the Antec Sonata case. Both power supplies are constructed with very similar goals in mind. They have a single 80mm fan to help keep the noise down and have very similar power specifications. The ZM400B-APS has a slightly higher 5v power rating that produces the 400W versus the 380W of the Antec unit. The important 12v rails are identical between the two.

The hardware that was used for the testing is listed below:

All readings for the voltage lines were done through the motherboard BIOS using the Motherboard Monitor 5 software application. The system was stressed for approximately 30 minutes straight using SiSoft Sandra's Burn-In process. Readings were taken every 30 seconds while the computer was functioning and the low and high values recorded.

Voltage levels on the Zalman unit were extremely good. The levels were actually closer to the specifications than the Antec True Power 380W unit that is supplied with the Sonata case. Fluctuation between the high and low was pretty minimal and all were within the acceptable ranges.

Noise from the fan unit was very low. Even during heavy loads where the power supply temperatures were likely to increase the fan noise, it was still lower than that of the other fans within the system. The specification states that the fan should generate between 20 and 25 dB during normal temperatures and a maximum of around 32dB at the highest temperatures.

Conclusions

Overall, the Zalman ZM400B-APS power supply performed very admirably. The voltages supplied across the three primary lines were all very close to the specifications and did not have a great amount of fluctuation. It provides sufficient power for pretty much any desktop configuration and produces very little noise. The only real drawbacks to this power supply are what comes with the package. It would be nice to see some sheathing on the power cables and a power supply fan RPM header for the motherboard to monitor the fan speed.

Manufacturer's Site