Phanteks AMP Series 550W Power Supply Review

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Tom's Hardware Verdict

The Phanteks AMP model with 550W achieves high performance and has a fairly quiet operation.


  • +

    Full power at 47 degrees Celsius

  • +

    High build quality

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    Satisfactory performance

  • +

    Dead silent

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    Fully modular (with 2x EPS connectors)

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    Compact dimensions


  • -

    Low 5VSB efficiency

  • -

    Transient response at 3.3V

  • -

    Small distance between the 4-pin Molex connectors

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The Phanteks Amps model with 550W capacity achieves high enough performance, and it is dead silent, thanks to its increased efficiency, over the previous Seasonic Focus Plus platform, and non-aggressive fan profile. It uses the new Focus Plus Gold platform, so besides higher efficiency, its protection features are also enhanced, especially the inrush current protection. The most notable competitors are the Corsair RM550x, the EVGA 550 G3, which soon enough won't be available, and of course, the similar capacity Seasonic Focus Plus Gold (GX-550) unit.

Phanteks cooperated again with Seasonic, and the outcome was the Amp series, which includes three models, with capacities ranging from 550W to 750W. All are based on the newest version of Seasonic's Focus Plus Gold platform, so we expect good performance and increase reliability, even under harsh conditions.

All Amps models, including the smallest model, come with two EPS connectors. Back in the day, most power supplies with less than 750W capacity only had one EPS, but the times change fast, so most brands chose to increase that number. It probably is an overkill for a 550W unit to have two EPS connectors since each of them can deliver up to 336W, and there are also two PCIe 6+2 pin connectors that can deliver up to 150W each. Still, it will make it future-proof and compatible with the majority of high-end mainboards that need extra juice for the CPU. 


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Manufacturer (OEM)


Max. DC Output



80 PLUS Gold, ETA-A (88-91%)


LAMBDA-A++ (<15 dB[A])


✓ (Fully)

Intel C6/C7 Power State Support

Operating Temperature (Continuous Full Load)

0 - 50°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 Fluid Dynamic Bearing Fan (HA1225H12F-Z)

Semi-Passive Operation

✓ (selectable)

Dimensions (W x H x D)

150 x 85 x 140mm


1.49 kg (3.28 lb)

Form Factor

ATX12V v2.4, EPS 2.92


10 Years

Power Specifications

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Max. PowerAmps20204530.3
Total Max. Power (W)550

Cables and Connectors

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Modular CablesCable CountConnector Count (Total)GaugeIn Cable Capacitors
ATX connector 20+4 pin (610mm)1118-22AWGYes
4+4 pin EPS12V (650mm)2218AWGNo
6+2 pin PCIe (750mm)2218AWGNo
SATA (420mm+150mm+150mm+150mm)2818AWGNo
SATA (300mm+150mm)1218AWGNo
4 pin Molex (450mm+120mm+120mm)1318AWGNo
4 pin Molex to SATA 3.3V Adapter (150mm+150mm)1218AWGNo
AC Power Cord (1370mm) - C13 coupler1118AWG-

All cables have sufficient length, and plenty of connectors are provided for the wattage of this unit. Our only complaint is the small distance between the 4-pin Molex connectors, which should be 160mm, at least. 

Component Analysis

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)Seasonic
PCB TypeDouble Sided
Primary Side
Transient Filter4x Y caps, 2x X caps, 2x CM chokes, 1x MOV, 1x Discharge IC
Inrush ProtectionNTC Thermistor & Relay
Bridge Rectifier(s)2x GBU1006 (600V, 10A @ 100°C)
APFC MOSFETS2x Champion GPT13N50D (500V, 13A, 0.49Ohm)
APFC Boost Diode1x NXP BYC8-600(600V, 8A @ 109°C)
Hold-up Cap(s)1x Hitachi (400V, 390uF, 2,000h @ 105°C, HU)
Main Switchers4x Champion GPT10N50AD (500V, 9.7A, 0.7Ohm)
APFC ControllerChampion CM6500UNX
Resonant ControllersChampion CM6901T6
TopologyPrimary side: Full-Bridge & LLC converter
Secondary side: Synchronous Rectification & DC-DC converters
Secondary Side
+12V MOSFETS2x Nexperia PSMN2R6-40YS(40V, 100A @ 100°C, 5.3mOhm @ 175°C)
5V & 3.3VDC-DC Converters
Filtering CapacitorsElectrolytics: 6x Nippon Chemi-Con (4-10,000h @ 105°C, KY), 3x Nippon Chemi-Con (1-5,000h @ 105°C, KZE), 2x Nichicon (2-5,000h @ 105°C, HD), 3x Nichicon (4-10,000h @ 105°C, HE)
Polymers: 9x FPCAP, 2x NIC, 4x United Chemi-Con
Supervisor ICWeltrend WT7527V (OCP, OVP, UVP, SCP, PG)
Fan ModelHong Hua HA1225H12F-Z (120mm, 12V, 0.58A, Fluid Dynamic Bearing Fan)
5VSB Circuit
Rectifier1xPFC P10V45SP SBR (45V, 10A)
Standby PWM ControllerExcelliance MOS EM8569

All AMP models are based on the second, and more recent, version of the Seasonic Focus Plus Gold line. 

The design is clean, and the small PCB is not densely populated. Hence the airflow is unobstructed. Moreover, the build quality is excellent, and the parts that Seasonic uses are of high quality as well. That's why the company is confident enough to provide such an extended warranty. 

The transient filter has two stages, as in the majority of PSUs, and it includes all necessary components. 

Both bridge rectifiers are bolted onto a small, dedicated, heat sink. 

Right in front of the APFC's converters FETs and boost diode, there is the NTC thermistor, responsible for protection against large inrush currents, and its bypass relay. 

There are four primary switching FETs, arranged into a full-bridge topology. It is rare to see a low-mid capacity PSU featuring this topology, which is mostly used in >1kW PSUs. 

The FETs that regulated the +12V rail are installed on the solder side of the PCB. The two heat sinks above them assist in their cooling. 

The minor rails are generated through two Voltage Regulator Modules (VRMs).

Besides electrolytic caps, with the majority of them having a pretty long lifetime, many polymer caps are also used for filtering purposes.

At the front of the modular board we find four polymer caps and three large electrolytic ones. 

The soldering quality is good.

Hong Hua provides reliable fans at reasonable prices, and this is why many OEMs prefer its products nowadays, including Seasonic of course. This specific model uses a fluid dynamic bearing, which offers a long lifetime. 

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Contributing Editor

Aris Mpitziopoulos is a Contributing Editor at Tom's Hardware US, covering PSUs.