Corsair RM750x 2021 – A Familiar Face With MegLev


Today we’ll be covering the new RMx 2021 from Corsair, a modified version of the RMx 2018. We’ve been provided a sample to analyze. They’re offering a newer version of the same platform with higher low-load efficiency, a new MegLev fan and an updated housing. How will it hold up and is it worth considering for your upcoming system?

General Specifications

ModelRM750x (2021)
Introduction year2021
Warranty10 years

Power Specifications


The usual can be seen once again here. It provides full capacity on the 12v rail and uses a single rail setup.


Cable typeCable countConnector countGaugeIn-cable capacitors
ATX 20+4 pin1116-20 AWGYes
EPS12v 4+4 pin2118 AWGYes
PCIe 6+2 pin2216-18 AWGYes
4-pin peripheral1418 AWGNo

Corsair gives you the cables you expect of a 750w these days. The only change I’d like to see is the same I asked for in the Aresgame AGT850 review, having another PCIe cable included to have 3 individual cables leading to the GPU. Just like the AGT, it includes dual EPS connectors, something overkill for most consumer CPUs, but still a widely requested feature.

The cables also feature in-cable capacitors. Some find these to be annoying because it makes the cables more stiff, but from the other side the capacitors do offer additional ripple filtering, which will show itself in later parts of this review.


Here we see the change most people will see between the 2019 and 2021 version. The outer design has been renewed to fit Corsair’s new general theme they’ve also applied to their RAM and other products. I’m personally more a fan of a simple mesh design because of it’s efficiency, but the current style gives it a very premium look.


OPPYes (WT7502R/IN1S313i)
OCPYes (WT7518)
OTPYes (IN1S313i)
UVPYes (WT7502R/IN1S313i)
OVPYes (WT7502R/IN1S313i)
SCPYes (WT7502R/IN1S313i)

The only minor thing we lack here is having the option for setting a multirail OCP, but otherwise this is better than usually is expected with even having 12v OCP integrated.

Parts breakdown

Input Voltage100-240v
Primary ConverterAPFC Half Bride LLC
RectifierSynchronous Rectification
FanCorsair NR140ML (12v, 0.27a)
BearingMagnetic Levitation
Rated Lifespan100k Hours (50c)
PCB TypeDouble Sided
Bulk Capacitors2x Nippon Chemi-Con (400v, 470+390uF, 105c)
Main Switches2x ON Semiconductor FCPF190N60E (600v, 13,1a, 100c)
APFC ControllerChampion CM6500UNX + CM03X
Resonant ControllerChampion CU6901VAC
12v MOSFETs6x ON Semiconductor NTMFS5C430N (40v, 131a, 100c)
DC-DC Converters2x UBIQ QM3054M6 (30V, 61A, 100c) + 2x QN3107M6N (30v, 70a, 100c)
DC-DC ControllerUPI Semi uP3861P
Filtering Capacitors (Electronic)14x Nippon Chemi-Con, 1x Rubycon
Filtering Capacitors (Polymer)33x Nichicon
Supervisor ICWeltrend WT7502R + WT7518 + Infinno IN1S313i
5VSB RectifierMakoSemi PS1045L + InPower Semiconductor ISD04N65A
Standby PWM ControllerOn-Bright OB5282

The RMx 2021 is very similar to it’s 2019 counterpart, the only major differences to see here being it’s fan and some minor changes to achieve higher low-load efficiency by using burst mode. As the RMx 2019 already performed very well, Corsair had little reason to make major changes to the platform, which means the dimensions and most of the parts are still the same high quality parts they’ve been providing.


Electrical Performance

Test Equipment

Electronic Loads4x Chroma 63601-5, 2x Chroma 63600-2, 20x 63640-80-80, 2x 63610-80-20
AC SourcesChroma 6530, Keysight AC6804B
Power analyzersN4L PPA1530 x2
Sound analyzerBruel & Kjaer 2270 G4
MicrophoneBruel & Kjaer Type 4955-A
Data loggers2x Picoscope TC-08, 2x Labjack U3-HV
Tachometer2x UNI-T UT372
Digital multimetersKeysight U1273AX, Fluke 289, Keithley 2015 - THD
UPSCyberPower OLS3000E 3kVA x2
Transformers3kVA x2

The equipment isn’t ours and testing done isn’t by us, but by a third party called Cybenetics and will be used in this review. You can find their efficiency standard ETA, noise standard LAMBDA, methodology, power supply database and more on their site. The results we’re showing here is based off the RM750x 2021 230v report.


LoadDC (Watt)AC (Watt)Efficiency
Low load 119.98925.02379.883%
Low load 239.97946.65285.696%
Low load 360.00868.28887.875%
Low load 479.95891.16587.707%
Load 174.98985.94187.256%
Load 2150.031164.91690.974%
Load 3225.037242.73292.710%
Load 4300.045323.10592.863%
Load 5374.594404.69192.563%
Load 6449.515487.67792.175%
Load 7524.858572.41991.691%
Load 8600.165658.34591.163%
Load 9674.714744.36190.643%
Load 10749.938832.89090.040%
Load 11825.169922.73289.427%
Crossload 1151.044180.59883.635%
Crossload 2760.207839.95590.506%

The unit easily reaches it’s promised level of 80+ gold, and with that also meets ETA Gold without any issue, just like the older RMx models did. One of the main differences from the old RMx is also visible here, showing a higher efficiency at low loads.

Efficiency 5vsb

LoadDC (Watt)AC (Watt)Efficiency
5VSB 10.2270.34865.230%
5VSB 20.4540.63971.049%
5VSB 32.7703.59876.987%
5VSB 45.0286.44278.050%
5VSB 57.5289.61678.286%
5VSB 614.96519.16778.077%

here too nothing underwhelming to be found. The unit shows efficiency well above 70% at lower loads outside of the first.

Voltage regulation – Amperage

Load12v amperage (A)5v amperage (A)3.3v amperage (A)5vsb amperage (A)
Low load 11.2390.4930.4990.197
Low load 22.4780.9901.0010.396
Low load 33.7201.4851.5010.595
Low load 44.9251.9822.0010.794
Load 14.4261.9812.0030.994
Load 29.8892.9753.0041.194
Load 315.7253.4733.5081.394
Load 421.5593.9704.0111.595
Load 527.0204.9655.0171.795
Load 632.5295.9626.0211.996
Load 738.0836.9577.0282.198
Load 843.6387.9588.0352.400
Load 949.5708.4598.5252.400
Load 1055.3108.9619.0463.009
Load 1161.6588.9679.0533.011
Crossload 10.11618.00117.9980.000
Crossload 262.5161.0001.0021.000

This shows the amperages each respective load test is done at. This isn’t very interesting on it’s own, but will help understanding the table below this.

Voltage regulation – Voltages

Load12v voltage (V)5v voltage (V)3.3v voltage (V)5vsb voltage (V)
Low load 111.9755.0723.3105.070
Low load 211.9765.0513.3005.046
Low load 311.9795.0483.2985.041
Low load 412.0545.0453.2965.036
Load 112.0565.0463.2965.032
Load 212.0475.0423.2945.027
Load 312.0185.0403.2925.023
Load 412.0065.0393.2915.018
Load 511.9945.0373.2905.015
Load 611.9985.0343.2895.011
Load 711.9675.0323.2885.006
Load 811.9565.0293.2865.002
Load 911.9475.0253.2845.000
Load 1011.9375.0223.2834.986
Load 1111.9285.0193.2814.983
Crossload 112.0215.0263.2885.077
Crossload 211.9475.0263.2835.012

And here is where the unit shines, showing a very tight voltage regulation on all rails, very close to nominal. Nothing to complain here.

Ripple measurements

Load12v (mv)5v (mv)3.3v (mv)5vsb (mv)Pass/Fail (ATX)
Load 14.903.503.305.30Pass
Load 24.703.402.905.10Pass
Load 38.103.503.004.90Pass
Load 47.203.703.205.50Pass
Load 56.603.703.005.70Pass
Load 66.407.209.807.90Pass
Load 76.703.903.705.30Pass
Load 86.704.406.605.50Pass
Load 96.204.907.105.50Pass
Load 108.905.107.106.60Pass
Load 119.505.309.006.20Pass
Crossload 25.304.508.006.30Pass

Here is where the unit really shines. Due to the use of in-cable capacitors the cables do get a bit more stiff, but it helps filter the ripple out together with the capacitors that are already in the unit itself. Showing no higher than 9.5 mv of ripple, this is well within the margin of ATX. ATX goes by the following:

  • 12v = 120mv max
  • 5v/3.3v/5vsb = 50mv max

Fan speed + noise

LoadFan speed (RPM)Noise (dBA)
Low load 10< 6
Low load 20< 6
Low load 30< 6
Low load 40< 6
Load 10< 6
Load 20< 6
Load 30< 6
Load 40< 6
Load 53627.3
Load 649110.9
Load 771221.0
Load 894229.7
Load 9121837.5
Load 10151542.6
Load 11191348.1
Crossload 159115.2
Crossload 2191248.1

This is sadly where a lot of my positive feedback about it’s performance stops for a bit. The unit isn’t extremly loud in any way, but is visibly louder at higher loads compared to it’s 2018 version. It still uses the same fan controller setup, but the fan and housing make the unit visibly louder. This is still within a more than acceptable margin, especially at lower loads. But as you push the unit, it’ll become quite a bit louder than it’s older brother.

Hold-up time

Hold-up timePower-OK timePower OK to DC loss delay
26.60 ms23.90 ms2.70 ms

Again, we have nothing to complain here. Corsair is well within ATX specification and the unit is well useable in combination with a UPS.


Overall, Corsair changed little about their RMx units with this new 2021 refresh, but that’s not a bad thing. Some of the changes like the burst mode controller make total sense, but sadly some of them are less beneficial to the unit. The new Meglev fan does improve potential lifespan of the unit, but makes the unit especially at higher loads noticably louder. Corsair is also recently going with a triangle-like pattern that visually might look nice, but makes it a bit more restrictive compared to the old housing design, and we expect this to also have a minor part in the increased noise levels compared to the 2018 version. Still, we’re overall very satisfied about it’s performance, build quality and protection set. The only thing is that Corsair has it’s competitors coming in from all sides, so it’s value over many other units can get debatable at times.

Either way, if you were planning to pick an RMx up, I can highly recommend it.

RM750x 2021




Internal quality




Electrical performance




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