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Gigabyte P550B Power Supply Review

An affordable PSU with mediocre performance.

Gigabyte P550B
(Image: © Tom's Hardware)

Advanced Transient Response Tests

For details about our transient response testing, please click here.

In the real world, power supplies are always working with loads that change. It's of immense importance, then, for the PSU to keep its rails within the ATX specification's defined ranges. The smaller the deviations, the more stable your PC will be with less stress applied to its components. 

We should note that the ATX spec requires capacitive loading during the transient rests, but in our methodology, we also choose to apply a worst case scenario with no additional capacitance on the rails. 

Advanced Transient Response at 20% – 20ms

VoltageBeforeAfterChangePass/Fail
12V12.122V11.798V2.67%Pass
5V5.083V4.868V4.23%Pass
3.3V3.312V2.999V9.45%Fail
5VSB5.076V4.957V2.34%Pass

Advanced Transient Response at 20% – 10ms

VoltageBeforeAfterChangePass/Fail
12V12.124V11.657V3.85%Pass
5V5.081V4.870V4.15%Pass
3.3V3.311V3.006V9.21%Fail
5VSB5.076V4.966V2.17%Pass

Advanced Transient Response at 20% – 1ms

VoltageBeforeAfterChangePass/Fail
12V12.124V11.727V3.27%Pass
5V5.080V4.888V3.78%Pass
3.3V3.311V3.000V9.39%Fail
5VSB5.075V4.953V2.40%Pass

Advanced Transient Response at 50% – 20ms

VoltageBeforeAfterChangePass/Fail
12V12.041V11.711V2.74%Pass
5V5.054V4.836V4.31%Pass
3.3V3.286V2.965V9.77%Fail
5VSB5.029V4.906V2.45%Pass

Advanced Transient Response at 50% – 10ms

VoltageBeforeAfterChangePass/Fail
12V12.043V11.652V3.25%Pass
5V5.052V4.826V4.47%Pass
3.3V3.285V2.971V9.56%Fail
5VSB5.028V4.937V1.81%Pass

Advanced Transient Response at 50% – 1ms

VoltageBeforeAfterChangePass/Fail
12V12.044V11.690V2.94%Pass
5V5.049V4.847V4.00%Pass
3.3V3.284V2.989V8.98%Fail
5VSB5.027V4.950V1.53%Pass
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Gigabyte P550B

(Image credit: Tom's Hardware)

Results 25-29: Transient Response

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Gigabyte P550B

(Image credit: Tom's Hardware)
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Gigabyte P550B

(Image credit: Tom's Hardware)
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Gigabyte P550B

(Image credit: Tom's Hardware)
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Gigabyte P550B

(Image credit: Tom's Hardware)
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Gigabyte P550B

(Image credit: Tom's Hardware)
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Gigabyte P550B

(Image credit: Tom's Hardware)
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Gigabyte P550B

(Image credit: Tom's Hardware)

Transient response is terrible on all rails, especially at 3.3V.

Turn-On Transient Tests

In the next set of tests, we measure the PSU's response in simpler transient load scenarios—during its power-on phase. Ideally, we don't want to see any voltage overshoots or spikes since those put a lot of stress on the DC-DC converters of installed components.

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Gigabyte P550B

(Image credit: Tom's Hardware)

Turn-On Transient Response Scope Shots

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Gigabyte P550B

(Image credit: Tom's Hardware)
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Gigabyte P550B

(Image credit: Tom's Hardware)

There is a small voltage overshoot at 5VSB, which is nothing to worry about. The 12V slopes are good. 

Power Supply Timing Tests

There are several signals generated by the power supply, which need to be within specified, by the ATX spec, ranges. If they are not, there can be compatibility issues with other system parts, especially mainboards. From year 2020, the PSU's Power-on time (T1) has to be lower than 150ms and the PWR_OK delay (T3) from 100 to 150ms, to be compatible with the Alternative Sleep Mode.

PSU Timings Table
T1 (Power-on time) & T3 (PWR_OK delay)
LoadT1T3
20%45ms289ms
100%78ms288ms

The PWR_OK delay is out of the 100-150ms region, so the PSU does not support the alternative sleep mode, which the ATX spec recommends. We didn't expect this unit to offer ASM support. 

Ripple Measurements

Ripple represents the AC fluctuations (periodic) and noise (random) found in the PSU's DC rails. This phenomenon significantly decreases the capacitors' lifespan because it causes them to run hotter. A 10-degree Celsius increase can cut into a cap's useful life by 50%. Ripple also plays an important role in overall system stability, especially when overclocking is involved.

The ripple limits, according to the ATX specification, are 120mV (+12V) and 50mV (5V, 3.3V, and 5VSB).

Test12V5V3.3V5VSBPass/Fail
10% Load11.8 mV10.0 mV11.1 mV13.1 mVPass
20% Load12.8 mV10.3 mV10.4 mV13.0 mVPass
30% Load13.3 mV8.7 mV10.1 mV13.3 mVPass
40% Load14.0 mV7.9 mV11.4 mV13.6 mVPass
50% Load20.4 mV9.9 mV13.4 mV17.7 mVPass
60% Load26.7 mV12.3 mV16.3 mV17.4 mVPass
70% Load33.3 mV14.1 mV16.5 mV20.3 mVPass
80% Load40.0 mV15.0 mV22.5 mV22.1 mVPass
90% Load54.2 mV17.6 mV21.1 mV25.0 mVPass
100% Load79.2 mV24.9 mV22.6 mV29.5 mVPass
110% Load108.5 mV33.5 mV23.6 mV33.3 mVPass
Crossload 119.2 mV17.1 mV27.1 mV23.3 mVPass
Crossload 287.2 mV22.9 mV16.9 mV24.6 mVPass
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Gigabyte P550B

(Image credit: Tom's Hardware)

Results 30-33: Ripple Suppression

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Gigabyte P550B

(Image credit: Tom's Hardware)
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Gigabyte P550B

(Image credit: Tom's Hardware)
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Gigabyte P550B

(Image credit: Tom's Hardware)

Ripple suppression is satisfactory on all rails but 12V, where it is much higher than what we would like to see. This platform is close to its limits with 550W output.

Ripple At Full Load

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Gigabyte P550B

(Image credit: Tom's Hardware)

Ripple Full Load Scope Shots

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Gigabyte P550B

(Image credit: Tom's Hardware)
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Gigabyte P550B

(Image credit: Tom's Hardware)
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Gigabyte P550B

(Image credit: Tom's Hardware)

Ripple At 110% Load

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Gigabyte P550B

(Image credit: Tom's Hardware)

Ripple 110% Load Scope Shots

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Gigabyte P550B

(Image credit: Tom's Hardware)
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Gigabyte P550B

(Image credit: Tom's Hardware)
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Gigabyte P550B

(Image credit: Tom's Hardware)

Ripple At Cross-Load 1

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Gigabyte P550B

(Image credit: Tom's Hardware)

Ripple CL1 Load Scope Shots

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Gigabyte P550B

(Image credit: Tom's Hardware)
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Gigabyte P550B

(Image credit: Tom's Hardware)
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Gigabyte P550B

(Image credit: Tom's Hardware)

Ripple At Cross-Load 2

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Gigabyte P550B

(Image credit: Tom's Hardware)

Ripple CL2 Load Scope Shots

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Gigabyte P550B

(Image credit: Tom's Hardware)
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Gigabyte P550B

(Image credit: Tom's Hardware)
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Gigabyte P550B

(Image credit: Tom's Hardware)

EMC Pre-Compliance Testing – Average & Quasi-Peak EMI Detector Results

Electromagnetic Compatibility (EMC) is the ability of a device to operate properly in its environment without disrupting the proper operation of other nearby devices.

Electromagnetic Interference (EMI) stands for the electromagnetic energy a device emits, and it can cause problems in other nearby devices if too high. For example, it can be the cause of increased static noise in your headphones or/and speakers.

(Image credit: Tom's Hardware)

The EMI filter does a good job, so conducted EMI emissions stay low. 

MORE: Best Power Supplies

MORE: How We Test Power Supplies

MORE: All Power Supply Content

  • refillable
    Nice one Aris! I have a request for you. Can you test the Seasonic S12III? It has been circulating around a year now and no one seems to be bothered testing it.
    Reply
  • Aris_Mp
    If I manage to find one, suree!
    Reply
  • NightHawkRMX
    I second this request for the S12iii. Given the popularity of the S12ii (at least back in the day), I am interested to see a review of the successor. I think the fact its RSY made kind of adds to my interest.
    Reply
  • NightHawkRMX
    Gigabyte GP-P750GM 750 W Review - With an Explosive Attitude | TechPowerUp
    Well, at least it did not explode.

    Gigabyte should just be banned from making PSUs at this point.
    Reply
  • Aris_Mp
    NightHawkRMX said:
    Gigabyte GP-P750GM 750 W Review - With an Explosive Attitude | TechPowerUpWell, at least it did not explode.

    Gigabyte should just be banned from making PSUs at this point.
    Yes this one didn't treat me with fireworks :)
    Reply