Zalman ZM300A-APF 300W Switching Power Supply Review

Bosco - 2007-01-26 19:02:27 in Power Supplies
Category: Power Supplies
Reviewed by: Bosco   
Reviewed on: November 30, 2002
Price: $70 USD


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


Taken from Zalman's website:
AC Input Requirements
AC Input Range Voltage 100VAC ~ 240VAC +-10%
Frequency 47Hz~63Hz
AC Input Current
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.


Test System:

  • Intel Pentium 4 2533MHz
  • ASUS P4S533 Motherboard
  • AOpen GeForce4 Ti4200 Video Card
  • Memory 512MB DDR333 (Samsung)
  • Maxtor 60GB 7200 ATA133
  • Four Case Fans
  • Sunbeam Cold Cathode Light
  • Running Windows XP Professional
  • All inside an Aspire Turbo Gamer case
  • The voltages were too unstable for me to take an accurate screenshot on full load, so I ended up capturing the results only when the computer is idle. I used Motherboard Monitor to take these readings.

    Readings on the Enermax 300W Whisper Power Supply

    Readings on the Zalman 300W Quiet Power Supply

    In terms of accuracy, I'd say that the voltages are pretty accurate, with the exception of the +12V line. By the same token, my Enermax readings of that line is also lower than the rest of the other readings... it may have something to do with my current configuration, but I can't say for sure. I've shared all of my cables evenly to prevent any particular rail from becoming overloaded. It could be the CPU itself, which in turn may be an indicator for me to pickup a 350W power supply, or even a 400W or 450W, to be on the safe side.

    In terms of noise, the quietness is incredible! I purposely turned off all my case fans, leaving only the fans on my video card, CPU, and the power supply itself, and the system is pretty much mute. Only if I deliberately concentrate on the noise will I hear it then. Overall I am quite pleased with the results.


    Once again Zalman comes out with another solution to the never-ending noise! While the unit has only one fan, it's incredibly quiet, and it gets the job done nicely. The Active PFC is a good addition to any power supply, but it's really difficult to justify paying more than $80CAD for only 300W, Active PFC or not. I like the multi-connector as well, because if my fans were originally 3-pin, I don't need to introduce additional cabling for the converters, and I can save up on using the 4-pin peripheral plugs at the same time.


  • Very quiet
  • Uses Active PFC
  • Lots of peripheral plugs
  • Cons

  • A bit expensive
  • Only one fan