Gigabyte P550B Power Supply Review

An affordable PSU with mediocre performance.

Gigabyte P550B
(Image: © Tom's Hardware)

Tom's Hardware Verdict

The Gigabyte P550B is affordable but you get what you paid for. This PSU has low performance and noisy operation.


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    Full power at 41 degrees Celsius

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    Properly configured OCP at 12V and 5V

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    Correctly set OPP

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    Low conducted EMI

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    Compact dimensions


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    Low performance

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    Low efficiency

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    No OTP

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    OCP at 3.3V is set too high

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    Very Low PF with 230V

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    Low-quality components

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    Lower than 17ms hold-up time

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    Short distance between peripheral connectors

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The Gigabyte P550B is an entry-level power supply targeted at low-budget builds. It uses a low-efficiency platform with low overall performance. The build quality is not great, either. You can get a much more capable product like the Corsair CX550 and the XPG Pylon with similar capacity with a few dollars more. The Cooler Master MWE Bronze 550 uses a much more advanced platform, offering notably higher performance levels.  The GB-P550B definitely is not material for our best PSU picks article, despite its reasonable price. 

The Gigabyte P550B has two more siblings, with 450W and 650W capacities, so it is the line's middle member. It uses a non-modular cable design to keep the production costs as low as possible. Unfortunately, modular cables weren't the only thing that needed to be removed to lower cost, so the platform, provided by MEIC, uses an older design. Group regulated power supplies are not ideal for modern PCs, which heavily load the 12V rail while the load on the minor rails is minimal unless you use lots of addressable RGB lighting, which takes power from 5V. 

Given the inflated prices in all PC components nowadays, affordable power supplies look even more attractive now. Nonetheless, you have to consider the low-efficiency levels that they offer along with the mediocre overall performance and, in some cases, the decreased reliability. Let's face it. There are no real bargains when it comes to highly-affordable PSUs. Compromises have to be made, and cost cuts usually affect more than just the modular cables. So we suggest you invest as much as possible in the power supply since this will be the heart of your system. 

Specifications of Gigabyte P550B

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Manufacturer (OEM)


Max. DC Output



80 PLUS Bronze, Cybenetics Bronze (82-85%)


Cybenetics Standard (40-45 dB[A])


Intel C6/C7 Power State Support

Operating Temperature (Continuous Full Load)

0 - 40°C

Over Voltage Protection

Under Voltage Protection

Over Power Protection

Over Current (+12V) Protection

Over Temperature Protection

Short Circuit Protection

Surge Protection

Inrush Current Protection

Fan Failure Protection

No Load Operation


120mm Rifle Bearing Fan (BK BDH12025S)

Semi-Passive Operation

Dimensions (W x H x D)

150 x 85 x 140mm


1.52 kg (3.35 lb)

Form Factor

ATX12V v2.52, EPS 2.92


3 Years

Power Specifications of Gigabyte P550B

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Max. PowerAmps181543.530.3
Total Max. Power (W)550

Cables & Connectors on Gigabyte P550B

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Native CablesRow 0 - Cell 1 Row 0 - Cell 2 Row 0 - Cell 3 Row 0 - Cell 4
DescriptionCable CountConnector Count (Total)GaugeIn Cable Caps
ATX connector 20+4 pin (560mm)1118-22AWGNo
4+4 pin EPS12V (600mm)1118AWGNo
6+2 pin PCIe (540mm+150mm)1218AWGNo
SATA (510mm+120mm+120mm)2618AWGNo
4-pin Molex (510mm+120mm+120mm) / FDD (+120mm)13 / 118-22AWGNo
Modular CablesRow 7 - Cell 1 Row 7 - Cell 2 Row 7 - Cell 3 Row 7 - Cell 4
AC Power Cord (1400mm) - C13 coupler1118AWG-

The cables are long enough for a mainstream PSU, and the number of provided connectors is satisfactory. The distance between the peripheral connectors should be 150mm.

Component Analysis of Gigabyte P550B

We strongly encourage you to have a look at our PSUs 101 article, which provides valuable information about PSUs and their operation, allowing you to better understand the components we're about to discuss.

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General Data-
Manufacturer (OEM)MEIC
PCB TypeSingle Sided
Primary Side-
Transient Filter4x Y caps, 2x X caps, 2x CM chokes, 1x MOV
Inrush ProtectionNTC Thermistor SCK-1R55 (1.5 Ohm)
Bridge Rectifier(s) 1x GBU1006 (600V, 10A @ 100°C)
APFC MOSFETs 2x Jilin Sino-Microelectronics JCS18N50F (500V, 11A @ 100°C, Rds(on): 0.27Ohm)
APFC Boost Diode 1x STMicroelectronics STTH8S06D (600V, 8A)
Bulk Cap(s) 1x Teapo (400V, 330uF, 2,000h @ 85°C, LH)
Main Switchers 2x Jilin Sino-Microelectronics JCS18N50F (500V, 11A @ 100°C, Rds(on): 0.27Ohm)
PFC/PWM Combo ControllerChampion CM6805BG
Topology Primary side: APFC, Double Forward Secondary side: Passive Rectification & Group Regulation
Secondary Side-
+12V & 5V SBRs4x Dyelec SBP30V60CT (60V, 30A)
3.3V SBR1x Jinan Jingheng Electronics SE3045LCT (45V, 30A @ 90°C)
Filtering Capacitors

Electrolytic: 4x Chn Cap (3-7,000h @ 105°C, TP), 1x Chn Cap (2-5,000h @ 105°C, TM), 5x YC (105°C, LE), 2x YC (105°C, TH)

Supervisor ICWeltrend WT7525 (OVP, UVP, OCP, SCP, PG)
Fan ModelBK BDH12025S (120mm, 12V, 0.18A, Hydraulic Bearing Fan)
5VSB Circuit-
Standby PWM ControllerPR6249H

MEIC provides the platform, and it uses a double forward topology on the primary side. In contrast, on the secondary side, we find passive rectification for 12V and a group-regulated scheme for the minor rails. The heat sinks are small for this PSU's efficiency levels, and this is why the fan speed profile is so aggressive. The parts that MEIC used don't inspire confidence since the bulk cap and the filtering caps on the secondary side are of low quality. 

The EMI/transient filter is complete, and it does a pretty good job. It also included an MOV for surge protection. There is also an NTC thermistor for protection against large inrush currents.

According to its manufacturer, the bridge rectifier can deliver up to 10A at 100 degrees Celsius, only if it is mounted on a copper plate heatsink. Gigabyte used an inferior aluminum heatsink to save some bucks, so this bridge cannot deliver its full potential. Nonetheless, we didn’t encounter any problems even during the overpower protection evaluation tests to hold the bridge rectifier. It would be nice, though, to see it bolted on a proper heatsink.

The APFC converter uses a pair of Jilin Sino-Microelectronics FETs and a single boost diode by STMicroelectronics. The major let down here is the Teapo bulk cap, which is rated at 85 degrees Celsius. 

The main FETs are two Jilin Sino-Microelectronics JCS18N50F, while the combo PFC and PWM controller is a Champion CM6805BG IC. 

Four Dyelec SBRs regulate the 12V and 5V rails. These rails are tied together, so you will have load regulation and ripple problems if the loads between 12V and 5V are highly unbalanced. Finally, the 3.3V rail is regulated by a single SE3045LCT SBR.

Unknown manufacturers provide the filtering caps on the secondary side, so we don't expect them to last long, especially under increased operating temperatures. 

The standby PWM controller is a PR6249H IC.

Gigabyte P550B

(Image credit: Tom's Hardware)

The supervisor IC is a Weltrend WT7525, offering all essential protection features but OTP. 

Soldering quality is quite good, especially if we take into account the price tag of this product. 

We are highly skeptical about the fan's quality. It claims to have a fluid dynamic bearing, but in the best-case scenario, it uses a rifle bearing. 

MORE: Best Power Supplies

MORE: How We Test Power Supplies

MORE: All Power Supply Content

Aris Mpitziopoulos
Contributing Editor

Aris Mpitziopoulos is a contributing editor at Tom's Hardware, covering PSUs.

  • 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.
  • Aris_Mp
    If I manage to find one, suree!
  • 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.
  • 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.
  • 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 :)