Nexus NX-4000 PSU

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June 15, 2003 -- by Mike Chin

Product Nexus NX-4000 400W Power Supply
Manufacturer Nexus / Fortron-Source
Supplier Nexustek Netherlands
MSP US$110

The Nexus NX-3000 PSU, reviewed here last fall, may arguably have become the most popular PSU ever marketed as a quiet PC component. Nexus is undoubtedly hoping to repeat their success with the NX-4000, a higher power follow-up. Note that the retail box is cosmetically identical to that of the NX-3000 except for the labeling. Why change a good thing?

If the Nexus NX-4000 looks familiar in the photos below, that's no surprise. Like ExoticPC's SilenX 400W, the last PSU to be reviewed here, the NX-4000 is also based on the Fortron-Source FSP400-60PFN. At least visually, the primary differences are the labels and a different fan.

The fan is a model DF1208SH by Dynaeon Industrial Co. Ltd. rated at 0.2A at 12VDC. A quick search on the Dynaeon web site failed to bring up this particular model, but several conclusions can be made from the information on hand:

The designation SH -- S most likely means it is a sleeve bearing, probably chosen because it rattles and chatters less than the ball-bearing version. The H usually stands for High Power or Speed.

The 0.2A current rating of the fan is close to the 0.18A rating of the 80mm "H" fans I found on Dynaeon's site. They are rated for 2900 RPM, 41 CFM (cubic feet per meter) and 34 dBA -- all of which fall in line with the characteristics of typical PSU fans.

There are intake vents only on the side opposite the fan. Many other PSUs, including the Nexus NX-3000, have vents on the "bottom" or cover as well. Airflow behaves much like liquid in that it takes the shortest path or least resistance, which means that excessive venting may actually reduce airflow over the HS by allowing the air to take shortcuts via the shortest path. Having the intake vents only on the back panel means the air is forced to travel the entire length of the heatsinks in the PSU before it is blown out. This is probably better for cooling.

The PSU has Active PFC, which is generally a good thing for electrical efficiency. It also has universal input voltage, which allows the unit to be used on any AC line in the world without switching manually.

From the Nexustek web site...


  • Real silent power supply, only 21.7 dB(A) in idle mode
  • High efficiency
  • Output over voltage protection
  • Short circuit protection on all output
  • Reset Table power shut down
  • Approved by: T√úV, CSA, UL, NEMKO, FCC, CB & CE
  • Internal 80mm fan with wiregrill
  • Unique coupling of internal heat sink to the case of the power supply to increase overall heat dissipation area
  • 100% burn-in under high ambient temperature (50C)
  • Vacuum-impregnated transformer
  • MTBF: 100K hours at 25C
  • 100% Hi-pot tested
  • Line input fuse protection
  • Active PFC
  • Complies with EN61000-3-2
  • AC input full range


  • Remote ON/OFF Control: The power supply shall accept a logic open collector level which will disable / enable all out put voltage (excluding +5V standby)
  • Temperature range: operating 0C~50C; storage -20C~+80C
  • Temperature coefficient: 0.01% / C
  • Transient response: output voltage recovers in less than 1ms max. following a 25% load change
  • Hold-up time: 17 ms minimum at full load & nominal input voltage
  • Dielectric withstand: input / output 1800VAC for 1 second, input to frame ground 1800 for 1 second
  • Humidity: 5~95% RH
  • Efficiency: 65% min. 70% typical, at full load
  • Power factor correction: > 0.96 at full load
  • Power good signal: turn-on delay 100ms to 500ms
  • Overload protection: 150% max.
  • Inrush current: 80A cold, 120A warm at 132 VAC
  • Over voltage protection: +5V : 6.82V(max.)
  • +3.3V : 4.5V(max.)

Output Characteristics

AC Input
100~240 VAC, 10-5A, 60-50 Hz
DC Output
Load Regulation
Line Regulation
Ripple + Noise
50mV P-P
50mV PP
120mV PP
120mV PP
100mV PP
50mV PP
Min Load
Normal Load
Max Load
Max Power
Max Power

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