Zalman ZM300A-APF 300W Switching Power Supply Review

Introduction

As the noise by the fans in our systems continue to get louder, more hair is pulled out of our heads for the mini-construction-site that we so hate, yet we keep adding more and more high-powered components in there to make it faster and hotter for our business and entertainment needs of today and tomorrow. Many companies such as Antec and Enermax have resorted to manufacturing "quiet" versions of their own fan products for a while, as most computer users have noticed. Continuing with the Zalman tradition of running a quiet system, today I will be looking at their super-quiet ZM300A-APF 300W switching power supply.

Just a plain-looking package

Specifications

Taken from Zalman's website:

AC Input Requirements
AC Input Range	Voltage	100VAC ~ 240VAC +-10%
	Frequency	47Hz~63Hz
AC Input Current (Rated)	115VAC	10A
	230VAC	5A
PFC Type	.	Active PFC
Power Factor	..	>85%(Typical) @ 115VAC
Inrush Current Limit (@ Cold start at 25Deg.C)	115VAC	60A
	230VAC	90A
Efficiency	..	75% minimum @ 230VAC (Full Load)

DC Output Voltage Regulations (at Full load)
Vout	Regulation Range
+5VSB	+-5%	+4.75V ~ +5.25V
+3.3VDC	+-5%	+3.14V ~ +3.45V
+5VDC	+-5%	+4.75V ~ +5.25V
+12VDC	+-5%	+11.4V ~ +12.6V
-12VDC	+-10%	-10.8V ~ -13.0V
-5VDC	+-10%	-4.50V ~ 5.50V

DC Output load Capacity
Vout	Output Load Rating			Combined Power
	Imin	Imax	Ipeak
+3.3VDC	0.3A	28A	.	180W	280W
+5VDC	0.1A	30A
+12VDC	0.0A	15A	18A	.
-12VDC	0.0A	0.8A	.		20W.
-5VDC	0.0A	0.3A
+5VSB	0.0A	2.0A

Their claim on the combined power of the +3.3V and +5V rails is 180W, which is 10W higher than the 170W stated on the 300W version of the Enermax quiet PS. Although I do not have the equipment to test such claims like the guys in the Munich Labs (who were actually trying to destroy the power supplies by overloading them with current), I trust that Zalman wouldn't make false claims if they are intent on maintaining their strong reputation.

The package contents

The package includes the power supply unit itself, a manual, a power cable, and something different: a "multi-connector" for your system fans, provided that they use the 3-pin motherboard plugs.

The power supply! That's a big rocker switch! Notice that there's no setting for 120V~240V?

Just a single fan this time, and the air is drawn from the back of the power supply, instead of the bottom, like many of the dual-fan power supplies. This may be a nuisance to some users, especially overclockers, because this power supply does not offer a quick "escape route" for the heat to escape from the bottom of the unit.

Unlike most 300W power supplies, this one uses Active Power Factor Correction (PFC). Unlike Passive PFC, Active PFC uses a circuit to correct power factor, and can theoretically obtain a power factor of over 95%, instead of the usual 75% found in Passive PFC. Active PFC also diminishes total harmonics, automatically adjusts to the current AC input voltage, and is capable of a full input voltage range. This level of complexity isn't easily achieved, however, and results in a significantly higher production cost, leading to a more expensive end-product.

Those are really big heatsinks!

The power supply cables

The power supply comes with 7 peripheral power connectors, 2 floppy connectors, the 6-pin AUX connector, the 4-pin ATX12V connector, the mainboard connector, but no fan RPM monitor cable. There's no mesh covering the cables on the mainboard connector either. The length of the cables should be long enough in all but the tallest of server towers, but a 21" tower should be the tallest you'd want to go with this power supply.

The multi-connector

Zalman has also included an interesting item in every power supply that they sell: The multi-connector. This special plug turns a single peripheral connector into four 3-pin fan plugs, two running off the 12V rail and the other two running off 5V. I'm not sure what I'd do with the 12V, but the 5V plugs mean the fan will generate less noise in operation. However, this also means that if your case fans originally ran off the 3-pin connector, you can save some peripheral plugs by using them with the multi-connector.