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Corsair RM750x (2021) Power Supply Review

The Corsair RM750x (2021) tops the performance charts.

Corsair RM750x (2021)
Editor's Choice
(Image: © Tom's Hardware)

Our Verdict

The new Corsair RM750x (2021) achieves top performance, isn't noisy, and is equipped with a top-notch ML fan.

For

  • + Full power at 47 degrees Celsius
  • + High overall performance
  • + Silent at low and mid loads
  • + Fully compliant with ATX v2.52
  • + Highly efficient at light loads
  • + Long hold-up time
  • + Low inrush current
  • + Magnetic Levitation fan
  • + Two EPS and four PCIe connectors
  • + Fully modular
  • + 10-year warranty

Against

  • - High OCP triggering points on the minor rails
  • - A small overall efficiency boost would be nice
  • - The fan speed profile could be even more relaxed
  • - In cable capacitors
  • - Small distance between peripheral connectors

It wasn't easy to deliver a better product than the existing RM750x (2018), but Corsair managed to do this, and the new model achieves notably better performance. Compared to the previous model, it loses in quietness, but you cannot call it noisy with 28 dBA overall noise output. All in all, this is an excellent power supply, so that it will replace the older RM750x in our Best PSU Picks article. Notable competitors are the XPG Core Reactor 750W and the Seasonic Focus GX-750

Corsair decided to make some notable changes in its RMx line, among the most popular ones in today's market. This was not an easy task since the existing RMx units only counted three years in production and delivered excellent performance and silent operation simultaneously. When you try to upgrade something that is already very good, you face many challenges since you also have to keep the budget under control. 

The new Corsair RMx (2021) line consists of five models with capacities ranging from 550W to 1000W, and the main differences with the previous models are depicted below. 

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Corsair RM750x

(Image credit: Tom's Hardware)

Product Photos

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Corsair RM750x

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Corsair RM750x

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Corsair RM750x

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Corsair RM750x

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Corsair RM750x

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Corsair RM750x

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Corsair RM750x

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Corsair RM750x

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Corsair RM750x

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We will look at the third stronger member of the new RMx line in today's review, with 750W capacity. The RM750x is made by Channel Well Technology, like the rest of the line, and all of its cables are modular. The external design looks nice, and the fan grille, with the triangle perforations, doesn't look so restrictive. The PSU's dimensions are normal, which is a good thing since the smaller the power supply, the higher the noise output. 

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Corsair RM750x

(Image credit: Tom's Hardware)

Product Photos

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Corsair RM750x

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Corsair RM750x

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Corsair RM750x

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Corsair RM750x

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Corsair RM750x

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Specifications of Corsair RM750x

Manufacturer (OEM)

CWT

Max. DC Output

750W

Efficiency

80 PLUS Gold, Cybenetics Gold (87-89%)

Noise

Cybenetics A- (25-30 dB[A])

Modular

✓ (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

Cooling

140mm Magnetic Levitation Fan (NR140ML)

Semi-Passive Operation

Dimensions (W x H x D)

150 x 85 x 160mm

Weight

1.64 kg (3.62 lb)

Form Factor

ATX12V v2.53, EPS 2.92

Warranty

10 Years

Power Specifications of Corsair RM750x

Rail3.3V5V12V5VSB-12V
Max. PowerAmps202062.530.3
Watts150750153.6
Total Max. Power (W)750

Cables & Connectors of Corsair RM750x

DescriptionCable CountConnector Count (Total)GaugeIn Cable Capacitors
ATX connector 20+4 pin (610mm)1116-20AWGYes
4+4 pin EPS12V (650mm)2218AWGYes
6+2 pin PCIe (600mm+150mm) 2416-18AWGYes
SATA (500mm+110mm+110mm+110mm)1418AWGNo
SATA (520mm+110mm+110mm)2618AWGNo
4-pin Molex (450mm+100mm+100mm+100mm)1418AWGNo
AC Power Cord (1400mm) - C13 coupler1118AWG-

There are two EPS and four PCIe connectors, which are enough to deliver the unit's full power without any issues. The number of peripheral connectors is increased, and our only complaint here is the small distance between the 4-pin Molex connectors. SATA drives' slots might be close to each other in most chassis, not in all, though, but this usually is not the case for the devices that take power from 4-pin Molex (e.g., case fans). Finally, the in-cable caps can be a headache during cable routing and management. 

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Corsair RM750x

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Cable Photos

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Corsair RM750x

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Corsair RM750x

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Corsair RM750x

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Corsair RM750x

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Corsair RM750x

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Corsair RM750x

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Corsair RM750x

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Corsair RM750x

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Corsair RM750x

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Component Analysis of Corsair RM750x

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.

General Data-
Manufacturer (OEM)CWT
PCB TypeDouble Sided
Primary Side-
Transient Filter4x Y caps, 2x X caps, 2x CM chokes, 1x MOV
Inrush ProtectionNTC Thermistor SCK-037 (3 Ohm) & Relay
Bridge Rectifier(s)2x GBU1506 (600V, 15A @ 100°C)
APFC MOSFETs2x On Semiconductor FCPF190N60E (600V, 13.1A @ 100°C, Rds(on): 0.19Ohm)
APFC Boost Diode1x Power Intergrations QH08TZ600 (600V, 8A @ 95°C)
Bulk Cap(s)2x Nippon Chemi-Con (400V, 470uF & 390uF each or 860uF combined, 2,000h @ 105°C, KMW)
Main Switchers2x On Semiconductor FCPF190N60E (600V, 13.1A @ 100°C, Rds(on): 0.19Ohm)
APFC ControllerChampion CM6500UNX & Champion CM03X
Resonant ControllerChampion CU6901VAC
TopologyPrimary side: APFC, Half-Bridge & LLC converter
Secondary side: Synchronous Rectification & DC-DC converters
Secondary Side-
+12V MOSFETs6x On Semiconductor NTMFS5C430N (40V, 131A @ 100°C, Rds(on): 1.7mOhm)
5V & 3.3V

DC-DC Converters: 2x UBIQ QM3054M6 (30V, 61A @ 100°C, Rds(on): 4.8mOhm) & 2x UBIQ QN3107M6N (30V, 70A @ 100°C, Rds(on): 2.6mOhm)
PWM Controllers: UPI Semi uP3861P

Filtering CapacitorsElectrolytic: 7x Nippon Chemi-Con (1-5,000h @ 105°C, KZE), 7x Nippon Chemi-Con (4-10,000h @ 105°C, KY), 1x Rubycon (4-10,000h @ @ 105°C, YXJ)
Polymer: 33x FPCAP
Change Over Switch1x Sync Power SPN3006 MOSFET (30V, 57A @ 100°C, Rds(on): 5.5mOhm)
Supervisor ICWeltrend WT7502R (OVP, UVP, SCP, PG)
Fan ControllerMicrochip PIC16F1503
Fan ModelCorsair NR140ML (140mm, 12V, 0.27A, Magnetic Levitation Bearing Fan)
5VSB-
Rectifier1x PS1045L SBR (45V, 10A) & IPS ISD04N65A
Standby PWM ControllerOn-Bright OB5282
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Corsair RM750x

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Overall Photos

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Corsair RM750x

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Corsair RM750x

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Corsair RM750x

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Like the RM1000x model, which we reviewed first, the OEM didn't change, so Channel Well Technology (CWT) makes the new RMx units. The platform has several differences to offer improved performance and ATX v2.52 compatibility. The major change is the new fan, and the PCB's dimensions haven't changed, so there was space for a 140mm fan, allowing for good airflow. 

The build quality is high, and CWT used good parts, including On Semiconductor FETs, Japanese caps by Chemi-Con and Rubycon, and lots of FPCAP polymer caps. 

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Corsair RM750x

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Transient filter

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Corsair RM750x

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Corsair RM750x

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Corsair RM750x

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Corsair RM750x

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Corsair RM750x

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Corsair RM750x

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The transient filter has all required parts to provide adequate protection and, at the same time, suppress both incoming and outgoing conducted EMI emissions. 

The inrush currents are suppressed by an NTC thermistor and relay combination, which does a good job. 

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Corsair RM750x

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Bridge rectifiers

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Corsair RM750x

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The bridge rectifiers are powerful and are installed on a dedicated heat sink, so they won't get too hot even under high loads and increased operating temperatures. 

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Corsair RM750x

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APFC converter

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Corsair RM750x

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Corsair RM750x

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Corsair RM750x

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Corsair RM750x

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The APFC converter uses two FETs, provided by On Semiconductor, and a single boost diode. The bulk caps are by Chemi-Con, and their combined capacity is high enough to provide for a longer than 26ms hold-up time. 

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Corsair RM750x

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Main FETs and primary transformer

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Corsair RM750x

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Corsair RM750x

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Corsair RM750x

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The main FETs are installed in a half-bridge topology, and an LLC resonant converter is also used to boost efficiency. The resonant controller is a Champion CM6901VAC IC. 

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Corsair RM750x

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12V FETs and VRMs

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Corsair RM750x

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Corsair RM750x

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Corsair RM750x

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Six FETs regulate the 12V rail while a pair of DC-DC converters generate the minor rails. 

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Corsair RM750x

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Filtering caps

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Corsair RM750x

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Corsair RM750x

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Corsair RM750x

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Chemi-Con mostly provides the filtering caps, so there won't be any issues in the long run. Besides electrolytic caps, we also find a large number of polymer ones by FPCAP. 

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Corsair RM750x

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5VSB Circuit

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Corsair RM750x

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Corsair RM750x

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The 5VSB rail uses an SBR on its secondary side, and the standby PWM controller is an On-Bright OB5282 IC.

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Corsair RM750x

(Image credit: Tom's Hardware)

Supervisor IC Board

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Corsair RM750x

(Image credit: Tom's Hardware)

The Supervisor IC is a Weltrend WT7502R, supporting all basic protection features but OTP (Over Temperature Protection). The latter is implemented through another circuit. 

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Corsair RM750x

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Modular Board

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Corsair RM750x

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Corsair RM750x

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There are several bus bars on the modular board for power transfers with minimized energy losses. Many polymer caps are also installed on this area for lower ripple on all rails. 

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Corsair RM750x

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Soldering quality

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Corsair RM750x

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Corsair RM750x

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Corsair RM750x

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Corsair RM750x

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Soldering quality is satisfactory, but in some areas of the PCB's finish doesn't look so good. 

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Corsair RM750x

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Cooling fan

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Corsair RM750x

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Corsair RM750x

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The major change between the previous and the new RMx generation is the Magnetic Bearing fan, able to withstand super-tough operating conditions without sweating. 

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  • RAZ0RLIGHT
    Is there any reason why the 2021 revisions fan curve is so much more aggressive?
    This would be the perfect Gold PSU if they would have implemented the same fan curve as the older 2018 revision.
    Reply