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Seasonic Gold Series X-750 Power Supply Review

Manufacturer: Seasonic

DC Load Regulation and AC Ripple

DC Output Load Regulation

To simulate real world and maximum loading conditions, the Seasonic Gold Series X-750  PSU was 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.

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

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As you can see, the X-750 Gold PSU produced outstanding load regulation on all of the outputs across a broad range of loads.  In my experience it just doesn't get much better than this!   

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AC Ripple and Noise on the DC Outputs

The amount of AC ripple and noise present on the DC outputs was checked using a digital oscilloscope.  This AC component may be present in the KHz range where most switching power supplies operate or it may be more prevalent at the 60 Hz line frequency.  We adjust the O-scope time base to look for AC ripple at both low and high frequencies.  The ATX12V V2.2 specification for DC output noise/ripple is defined in the ATX12V Power Supply Design Guide.

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Ideally we would like to see no AC ripple (repetitive) or noise (random) on the DC outputs – the cleaner the better!  But in reality there will always be some present.  I measured the amplitude of the AC signal (in millivolts, peak-to-peak) to see how well the power supply complied with the ATX standard.  The following table lists the ripple/noise results during all of the load tests for the main output voltages of interest.

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The Seasonic Gold Series X-750 power supply exhibited excellent AC ripple suppression on all of the primary outputs and stayed well below the recommended values, even at full load.
 

February 6, 2013 | 07:07 PM - Posted by Freshie

Are you going to review the x-850 too?

February 7, 2013 | 07:13 AM - Posted by Skidmarks (not verified)

Seasonic's PSU's are excellent. The only brand I use.

February 15, 2013 | 02:16 PM - Posted by John Doe (not verified)

Then you should maybe not judge things by their brand like a moron and start buying PSU's from other companies.

February 17, 2013 | 08:14 PM - Posted by bdfun2662

I have had this unit for a couple of months now and I have had zero problems so far. I got it at newegg on a super sale for $107.50 delivered to my door. It is overkill for my Sabertooth R2 8350 (4.5), MSI 7850 (1000 and 1250), 2 7200 rpm HDD, 1 Vertex4 128 GB, LiteON BD burner and 8 PWM fans. The most I seem to be using is a little over 350 watts and that is when I am ripping a BD disc and converting it to an MKV file about half the size. I had higher overclocks on both my CPU and GPU but I backed them down to a point where they run close to normal temps. I do believe that in order to obtain high stable overclocks you need a very good power supply and this is one.

March 30, 2013 | 05:07 AM - Posted by Anonymous (not verified)

I have this KM3 baby. Very solid power under load and keeps system running over minor power interruptions. (e.g. thunderstorms)

Really, really love this beast.

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