Seasonic SS-400H1U & SS-460H2U Power Supply Review

Introduction and Features

If you are into building, upgrading or maintaining servers check out our review of two PSU offerings from Seasonic. We’ll be taking a close look at two units; a 1U-400W and a 2U-460W. See how they compare to the more familiar enthusiast ATX units.

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)