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

DC Load Regulation

One of the first things we want to see is how well these two PSUs can regulate the DC outputs and maintain stable voltages.  To simulate real world and maximum loading conditions, the Seasonic PSUs were connected to the load testers and supplied with a constant 115 VAC.  In this test we are interested in seeing how well a PSU can maintain the various output voltages while operating under different loads. 

The ATX12V V2.2 tolerance for voltages states how much each output (rail) is allowed to fluctuate and has tighter tolerances now for the +12V outputs.  I have also included a second table of expanded tolerances (±1% to ±6%) for reference.


The following tables list the DC voltage results for the two PSUs while operating on 115 VAC, 60 Hz.

Seasonic SS-400H1U


The SS-400H1U produced excellent load regulation on all of the outputs across the entire load range; even when delivering the maximum rated capacity of 400 watts DC power.  The four primary rails were very close to staying within 1% or better.

•    +3.3V        (3.31 to 3.28)            +0% to -1%
•    +5V           (5.00 to 4.96)            +0% to -1%
•    +12V1        (12.12 to 12.02)        +1% to -0%
•    +12V2        (12.12 to 11.94)        +1% to -1%
•    -12V           (-12.10 to -12.45)        +0% to -4%
•    +5VSB        (4.92 to 4.78)            +0% to -5%


Seasonic SS-460H2U


The SS-460H2U also produced excellent load regulation on all of the outputs across the entire load range; even when delivering the maximum rated capacity of 460 watts DC power.  And again, the four primary rails were very close to staying within 1% or better.

•    +3.3V        (3.30 to 3.26)            +0% to -1%
•    +5V           (5.01 to 4.95)            +0% to -1%
•    +12V1       (12.09 to 11.95)        +1% to -1%
•    +12V2       (12.08 to 11.88)        +1% to -1%
•    -12V          (-12.01 to -12.49)      +0% to -4%
•    +5VSB       (4.93 to 4.79)            +0% to -5%