Seasonic Focus Plus 750 Gold PSU Review

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Ripple Measurements

To learn how we measure ripple, please click here.

The following table includes the ripple levels we measured on the SSR-750FX's rails. The limits, according to the ATX specification, are 120mV (+12V) and 50mV (5V, 3.3V, and 5VSB).

Test12V5V3.3V5VSBPass/Fail
10% Load8.9mV6.0mV8.2mV5.7mVPass
20% Load12.7mV6.1mV8.5mV5.9mVPass
30% Load15.2mV6.3mV8.5mV6.1mVPass
40% Load17.1mV7.8mV10.4mV6.5mVPass
50% Load18.3mV7.8mV9.1mV6.5mVPass
60% Load20.2mV10.4mV10.6mV7.2mVPass
70% Load21.9mV11.4mV11.6mV8.4mVPass
80% Load23.0mV11.6mV11.8mV9.4mVPass
90% Load26.2mV13.1mV13.1mV9.8mVPass
100% Load27.9mV13.2mV14.6mV11.6mVPass
110% Load28.6mV15.4mV15.9mV12.2mVPass
Cross-Load 112.3mV11.3mV9.4mV8.2mVPass
Cross-Load 227.2mV10.6mV12.8mV9.2mVPass
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The addition of filtering caps on the modular cables, along with a good overall design, enable impressive ripple suppression. Seasonic still doesn't achieve Super Flower levels, but it'd be silly to complain. Even under 110% load, the +12V rail doesn't exceed 30mV, while the minor rails stay below 16mV in the worst-case scenario.

Ripple Oscilloscope Screenshots

The following oscilloscope screenshots illustrate the AC ripple and noise registered on the main rails (+12V, 5V, 3.3V and 5VSB). The bigger the fluctuations on the screen, the bigger the ripple/noise. We set 0.01 V/Div (each vertical division/box equals 0.01V) as the standard for all measurements.

Ripple At Full Load

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Ripple At 110-Percent Load

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Ripple At Cross-Load 1

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Ripple At Cross-Load 2

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Aris Mpitziopoulos
Aris Mpitziopoulos

Aris Mpitziopoulos is a Contributing Editor at Tom's Hardware US, covering PSUs.
7 Comments Comment from the forums
  • none77
    Thank you for the detailed review.
    In the transient response test
    Advanced Transient Response at 50 Percent – 200ms
    the +3.3 pass.
    Reply
  • BugariaM
    As always, here are the most detailed reviews on the PSU.
    Thank you and keep it up!

    The only thing that is not quite clear to me. What is the criterion for voltage drop in % to get PASS/FAIL in "Advanced Transient Response Tests"?

    You declare that:

    "In all tests, we measure the voltage drops." The voltages should remain within the ATX specification's regulation limits. "

    For ATX 2.2 we have:

    12v - 10%
    5v - 5%
    3.3v - 5%
    5VSB - 5%


    However, looking at your reviews, there are often situations where, at <5%, the power supply gets the FAIL mark and vice versa, some at >5% receive PASS

    Why is this happening?
    Reply
  • BugariaM
    Sorry, a typo
    Of course for 12v - 5%
    Reply
  • Aris_Mp
    the limit is 5% however the voltage rails of the PSUs' under test in the majority of cases aren't at the nominal voltages, but higher, so even with 5% deviation voltages go don't bellow the limits that the ATX spec sets (11.4V, 4.75V, 3.14V). Only if a rail goes below those voltage levels it fails. The 5% is just an indication that the ATX provides to specify the voltages above.
    Reply
  • BugariaM
    Now everything became clear to me.
    Thank you.
    Reply
  • fredlaso
    Dell Inspiron 5675 Desktop, PSU (power supply unit), upgrade. Would this PSU compatible with Dell Inspiron 5675 Desktop. It came with 460W I would like to replace it with PSU between 650 to 750W. I tried at Dell forums but cannot get a clean link which one would be compatible.

    I would greatly appreciate if someone could help me out. Thank you kindly in advance:

    http://en.community.dell.com/support-forums/desktop/f/3514/t/20019321?pi21953=1#21018407
    http://en.community.dell.com/support-forums/desktop/f/3514/p/20024419/21031446#21031446

    System Comp,:
    Compatible Power Supply needed for Inspiron 5675 Gaming Power Supply
    Specs:

    AMD Ryzen 7 1700X 3.4GHz Octa-Core Processor
    8GB 2400MHz DDR4 RAM
    1TB 7200 RPM Hard Drive
    AMD Radeon RX 580 8GB GDDR5 Graphics Card
    DVD+RW Drive
    Dual Band WiFi 802.11ac + Bluetooth 4.1
    Windows 10 Home (64-bit)
    460 Watt Power Supply w/ Polar Blue LED
    Includes: Dell KB216 Wired Keyboard + Dell MS116 Wired Mouse
    Ports:
    6x USB 3.0
    1x USB 3.1 Type-C Gen 1
    2x USB 2.0
    1x Audio Combo Jack
    1x 3-in-1 Media Card Reader
    1x P/S 2
    1x 7.1 Channel Audio Out
    Expansion Slots:
    3x 3.5" bay
    2x 2.5" bay
    2x PCIe x1
    2x PCIe x16

    http://en.community.dell.com/support-forums/desktop/f/3514/t/20019321?pi21953=1#21018407
    http://en.community.dell.com/support-forums/desktop/f/3514/p/20024419/21031446#21031446
    Reply
  • paulinosaka
    My Seasonic Platinum began failing under load after only 10 months. Paid cash here in Japan at Joshin - couldnt find reciept - honestly never thought I would need it ever. Seasonic would not help me.?
    REPLY
    Reply