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OCZ ZT Series 550W PSU Review

In order to provide you with the most professional and accurate reviews, we are using the following equipment to test the performance of power supplies:

  • Modified SECC steel case with thermal generation and control components installed
  • Custom USB controlled DC load, 2.2KW maximum power drain
  • Lutron DW-6091 Power Analyzer
  • USB Instruments Stingray Oscilloscope
  • SL-5868P digital sound level meter
  • CompuLAB interface
  • MyPClab thermal interface
  • Labjack U3-HV interface
  • Custom calibration box
  • Custom software

More information about our testing equipment and methodology can be found in this article.


The OCZ ZT Series 550W unit successfully completed all of our tests without any operational and/or performance problems. The electrical performance of the power supply is great, with the voltage ripple barely reaching for 30mV with the power supply running at maximum load, although the voltage regulation is a little looser than most enthusiasts would expect.

The ZT 550W model manages to reach a very high efficiency of 88.6% under nominal load and it maintains a very high efficiency across the entire load range, although there is a significant drop of more than 3% when the power supply is heavily loaded.

Because of the high electrical efficiency and the strong cooling fan, the thermal performance of the ZT Series 550W unit is amongst the best we have ever encountered. The power supply barely reached a temperature delta of 16.7°C under maximum load.

It would seem that OCZ wanted to keep their unit running cool but not necessarily quiet. The ZT Series 550W power supply runs entirely silent but up to nominal load only; at 60% load the unit starts becoming audible and the noise rises geometrically as the load increases, ending up at a notably loud 45.8dB(A) under maximum load. 

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