Introduction and Features

Zalman’s newest modular power supply supports dual-core CPUs, dual graphic cards, and uses heat pipe technology to enhance cooling and minimize noise. The ZM600-HP proved to be very stable, efficient and quiet – highly recommended.

The ZM600-HP power supply is the latest addition to Zalman’s line of PC switching power supplies.  It features modular cables, support for dual CPUs and dual graphic cards, and can deliver up to 600 watts of continuous DC output.  The ZM600-HP uses a heat pipe to augment the internal cooling system for increased reliability and to reduce noise.  While not the first PSU manufacturer to take this approach, Zalman certainly has a strong history of effectively using heat pipes in many of their CNPS (Computer Noise Prevention System) enabled products.


Zalman ZM600-HP 600W Modular Heat Pipe Cooled PSU Review - Cases and Cooling 33


Zalman has a well earned reputation in the PC industry for delivering high-quality components that are designed to reduce noise.  In addition to PC power supplies, Zalman also offers desktop and HTPC enclosures, air and water-cooling solutions, along with numerous noise fighting accessories for the PC enthusiast.


Zalman ZM600-HP PSU Key Features:


  • 600 watt continuous power output
  • Heat pipe technology used to enhance cooling
  • Quiet 120mm cooling fan
  • ATX12V v2.2 and EPS12V support
  • Quad +12V outputs (up to 42A/504W combined +12V)
  • Dual PCI-e 6-pin connectors (nVidia SLI Ready)
  • Industrial grade components
  • High efficiency (up to 84%)
  • Modular cables aid cable management
  • EZ grip connectors with gold plated terminals
  • Internal blue LEDs and sleeved cables
  • Active PFC with Universal AC line input
  • 3-Year warranty 

In addition to the modular power supply the colorfully printed box includes a power cord, mounting screws, ZM-MC1 fan adapter, a printed User’s Manual, and seven modular cables. 


Zalman ZM600-HP 600W Modular Heat Pipe Cooled PSU Review - Cases and Cooling 34


Heat Pipe Technology


The Zalman ZM600-HP power supply uses a single copper heat pipe to transport heat from the secondary stage rectifiers over to an array of aluminum fins that is cooled by air exhausting out the back of the power supply.  Zalman isn’t the first company to use heat pipes to help cool a power supply.  Both Silverstone and Thermaltake used heatpipes in their fan-less PSU’s several years ago. 


A heat pipe is a highly efficient conductor of heat and using one in this manner greatly increases the effective surface area of the internal heatsink.  A properly constructed heat pipe has a very low thermal resistance, which is roughly independent of its length (unlike ordinary metal rods whose thermal resistance increases with length).  Heat pipes are commonly used to transport heat from one location to another.


Zalman ZM600-HP 600W Modular Heat Pipe Cooled PSU Review - Cases and Cooling 35                


Heat pipes work on the principle of evaporation and condensation.  A working fluid (frequently distilled water) evaporates inside one end of the heat pipe (the hot-end) absorbing heat in the process.  A partial vacuum inside the heat pipe allows the water to evaporate at low temperatures.  Once formed, the water vapor diffuses from an area of high vapor pressure (where it is being generated) to the other end of the tube where the vapor pressure is lower.


The vaporized fluid then condenses back to liquid (cold-end) and the heat is dissipated into the air from the metal cooling fins.  The working fluid returns to the hot end via capillary action thru an internal wicking structure (sintered metal coating, fine wire mesh, or grooves) so the heat pipe does not have to rely on gravity to recycle the working fluid.  The key to a heat pipe’s high efficiency is the latent heat of vaporization.


The Zalman 600W heat pipe power supply was evaluated on both features and performance.  A full range of equipment was used to test the power supply under controlled load conditions.  In addition to measuring the power going in and coming out I looked at voltage regulation, electrical noise (AC ripple), sound level, efficiency and cost.  Here is a list of the equipment used during testing.


Zalman ZM600-HP 600W Modular Heat Pipe Cooled PSU Review - Cases and Cooling 36


  • FLUKE 87-III True RMS digital multimeter (Accuracy ±0.05%)
  • Extech 380803 Power Analyzer (Accuracy ±0.5% of full scale)
  • Hitachi V-650F 60 MHz dual trace oscilloscope (Accuracy ±3%)
  • Powerstat Variable Autotransformer, 1.4 KVA, 0-140 VAC
  • FLUKE  52-II digital thermometer (Accuracy ±0.3ºC/0.5ºF)
  • Extech Model 407736 digital sound level meter (Accuracy ±1.5 dB)
  • AccuLab V1-10kg digital balance (Accuracy ±1g)
  • Homemade PSU load tester — selectable loads (up to 470W)
  • (2) CSI3710A Programmable DC load (up to 150W each)
  • (2) CSI3711A Programmable DC load (up to 300W each)

Establishing a controlled load is critical to testing and evaluating a PC power supply.  In addition to my own home-made load tester, I’m now using four programmable DC loads for greater flexibility and accuracy.  This new combination can place up 1,400 watt load on the unit being tested. 



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