Corsair RM550x Power Supply Review

A Look Inside And Component Analysis

Parts Description

Before proceeding with this page, we strongly encourage you to 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. Our main tools for disassembling PSUs are a Thermaltronics soldering and rework station, and a Hakko 808 desoldering gun.

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There are only three heat sinks: a very small one for the bridge rectifier and two thin ones without any fins. The first of those is for the APFC FET and diode, while the second is for the primary switchers. On the secondary side, the +12V FETs are cooled by the PCB that holds them and two metallic bars. The minor rails are generated by two DC-DC converters installed on a large vertical daughterboard.

Channel Well Technology (CWT) is the OEM that Corsair uses for its RM, RMi and RMx units. Inside, the RMx platform is similar to the RMi. Of course, there is no digital interface to facilitate monitoring and fan control. And although the RMi PSUs are equipped with a fluid dynamic bearing (FDB) fan, the RMx models use a lower-quality rifle bearing fan.

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On the AC receptacle, two Y caps form the first part of the EMI filter. The latter continues on the main PCB with two more Y caps and two X ones, two CM chokes and an MOV. The EMI filter on the main PCB is protected by a copper shield to further suppress EMI noise. If this shield was grounded, it would definitely do a better job.

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A small heat sink dissipates thermal energy from the single bridge rectifier, a GBU1506. This rectifier can handle up to 15A of current, so it covers the RM550x's needs.

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The APFC converter uses a single Vishay SIHG30N60E FET and Panjit SiC04A065T boost diode. The bulk cap is by Chemi-Con (400V, 470uF, 2000h @ 105 °C, KMQ), and its capacity looks to be ideal for the RM550x. In front of the PFC, coil we find a small NTC thermistor that provides protection against large inrush currents. Although a bypass relay isn't used, we suspect that the diode right beside it somehow isolates it from the circuit once the PSU starts.

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A small daughterboard houses the APFC controller, an Infineon ICE3PCS01G that's backed up by a CM03X Green PFC controller. On the same board, there's also an Infineon ICE2HS01G LLC resonant controller.

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A couple of Infineon IPA50R280CE FETs are the primary switchers; they're arranged into a half-bridge topology.

Here are the inductive and capacitive parts of the LLC resonant converter.

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The lack of any heat sinks on the secondary side makes quite an impression. This might be an efficient Gold-rated power supply, but we still expected at least a small sink for the +12V FETs. CWT obviously had a different opinion, and Corsair must be very confident about its design or it wouldn't offer such a long warranty.

The FETs that generate the +12V rail are four Sinopower SM4021NAKPs, all installed on a small PCB. The board and two metallic bars help cool these FETs. We also noticed that two short, thick cables connect the main transformer's output with the +12V PCB, minimizing energy losses.

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Four Chemi-Con electrolytic caps (rated at 105 °C) filter the +12V rail. All of the PSU's other filtering caps come from the same manufacturer.

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The PCB shown in the photos above houses both DC-DC converters responsible for generating the minor rails. The common PWM controller is an Anpec APW7159. In total, two M3006D and four M3004D FETs are used.

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The supervisor IC is a Weltrend WT7502 IC, which is installed on the main PCB. This IC provides only the very basic protections including OVP, UVP and SCP for the minor rails. More than likely, CWT uses another circuit to implement +12V protection features.

The 5VSB rail is regulated by a PFR20V45CT Schottky Barrier Diode (SBR) installed on the PCB's component side. The standby PWM controller (an On-Bright OB5269 IC) is installed on the solder side of the main PCB. Right next to it is a M03N65D FET; we don't know what purpose it serves.

The RMi family's MCU board is populated with a PIC32MX, which is the brains of the digital interface. That IC is missing in the RMx line-up. And because the cooling fan isn't PWM-controlled, its fan header only has two pins instead of four.

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On the front side of the modular PCB, many Chemi-Con capacitors provide an extra layer of ripple suppression.

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A number of cables on the back of the modular board transfer power. We also spotted a single M3004D FET back there.

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Overall, the soldering quality is pretty good.

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Here are some closer shots of the main PCB's solder side. We noticed two current shunt resistors under the +12V islands, suggesting that this platform can support OCP for at least two +12V rails with the proper supervisor IC. There is space on the modular PCB for two extra supervisor ICs, which you find installed on members of the RMi family.

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Again, Corsair uses a rifle bearing fan on its RMx units in an effort to lower their prices. The NR135L (135mm, 12V, 0.22A) is a low-speed fan featuring quiet operation, even when it's spinning quickly.