Seasonic has an excellent reputation for producing quiet ATX style PC power supplies with high efficiencies and stable outputs.  However, Seasonic also has a full line of server style power supplies in both 1U and 2U form factors.  In this review we will be taking a detailed look at both a 1U-400W and a 2U-460W server style power supply.  It will be interesting to see how these industrial grade units compare to the more familiar ATX style units built by Seasonic.

The Seasonic SS-400H1U and SS-460H2U server style power supply units are share many common features.  The main differences between the two units are the rated output capacity and the form factor.  The SS-400S1U can deliver up to 400W and is designed to fit in a slim 1U rack mount chassis while the larger SS-460H2U can produce up to 460W DC output and fits in a taller 2U chassis.  Because of the size difference, the 1U-400W unit uses two 40mm fans and the 2U-460W uses a single 60mm fan for cooling.

Seasonic SS-400H1U and SS-460H2U Main Features:

Seasonic SS-400H1U and SS-460H2U Special Features:

PSU Testing Methodology



Establishing an accurate load is critical to testing and evaluating a PC power supply.  PCPerspective’s power supply test bench can place a precise 2,000 watt DC load on the PSU under test.  Each power supply is tested under controlled, real-world conditions up to its maximum rated load, using both 115 VAC and 240 VAC line voltage.  Our current suite of tests includes:

•    DC Load Regulation

•    DC Line Regulation

•    DC Cross-load (unbalanced load)

•    AC Ripple and Noise

•    Power Factor

•    Efficiency

•    Differential Temperature

•    Noise

The Seasonic server style PSUs were evaluated on both features and performance.  A full range of equipment was used to test the power supply under controlled load conditions. 

•    (2) CSI3710A Programmable DC load (+3.3V and +5V outputs)

•    (4) CSI3711A Programmable DC load (+12V1, +12V2, +12V3, and +12V4)

•    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 407738 digital sound level meter (Accuracy ±1.5 dB)