Corsair RM1000x (2021) Power Supply Review

The Corsair RM1000x is one of the best Gold PSUs in this Wattage category.

Corsair RM1000x
(Image: © Tom's Hardware)

Tom's Hardware Verdict

The new Corsair RM1000x achieves high performance, and it keeps its noise output low. Moreover, it is highly efficient at light loads and comes with a top-quality fan.


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    + Full power at 47 degrees Celsius

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    + High overall performance

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    + Quiet operation

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    + Fully compliant with ATX v2.52

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    + Highly efficient at light loads

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    + Long hold-up time

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    + Low inrush current

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    + Magnetic Levitation fan

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    + Loads of cables and connectors

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    + Fully modular

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    + 10-year warranty


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    High OCP triggering points on the minor rails

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    A small overall efficiency boost would be nice

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    In cable capacitors

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    Small distance between peripheral connectors

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The Corsair RM1000x achieves high performance, and it isn't noisy, despite its increased max power output. It uses quality parts, including Japanese caps and a Magnetic Levitation fan, ideal for operation under high operating temperatures. It is fully compatible with the newest ATX spec (2.52), so among others, it offers high efficiency under super-light loads, and it also supports Microsoft's Modern Standby, which allows for speedy wake-from-sleep times (you also need a compatible motherboard). This is one of the best 1000W Gold PSUs, and if it weren't for the Corsair AX1000, it would easily get a spot in our best PSU's picks article. A strong opponent for this product is the Super Flower Leadex V Gold with a similar capacity.

Corsair decided to revamp its more successful line in the upper-range category. The RMx models managed to steal the spotlight from the higher-end RMi units since they offered a better performance per price ratio. The last time Corsair refreshed this line was three years ago, in 2018. PSUs have a much longer lifetime than other IT products, but in this case, Jon Gerow, Corsair's R&D PSU director, decided that it was high time for some changes. 

Besides the change from a rifle bearing to a more durable (and more expensive as well) fan, the new RMx units are fully compatible with the newest ATX spec, so they have over 70% efficiency with 2% load, and the PWR_OK delay is within the 100-150ms region, to support the Alternative Sleep Modes (ASM), including Microsoft's Modern Standby mode. 

The strongest member of the RMx line has 1000W max power so that it can be the heart of a demanding system, equipped with a potent CPU and a pair of graphics cards (not a pair Nvidia RTX 3080/90  or a pair of AMD RX 6800/6900 XT VGAs, though). For gaming purposes, using two graphics cards is next to useless. However, in some applications, still, multiple GPUs bring huge performance gains (e.g., rendering applications like the OctaneRender, VRAY GPU, and Redshift).  

Externally the differences between the old and new RMx units are notable. The fan grille is different, and the same goes for the front exhaust. Both use triangular perforations, which look nice.   


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Manufacturer (OEM)


Max. DC Output



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


Cybenetics A- (25-30 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


140mm Magnetic Levitation Fan (NR140ML)

Semi-Passive Operation

Dimensions (W x H x D)

150 x 85 x 180mm


1.99 kg (4.39 lb)

Form Factor

ATX12V v2.52, EPS 2.92


10 Years

Power Specifications

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Max. PowerAmps202083.330.3
Total Max. Power (W)1000

Cables & Connectors

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Modular CablesRow 0 - Cell 1 Row 0 - Cell 2 Row 0 - Cell 3 Row 0 - Cell 4
DescriptionCable CountConnector Count (Total)GaugeIn Cable Capacitors
ATX connector 20+4 pin (610mm)1116-20AWGYes
4+4 pin EPS12V (650mm)3318AWGYes
6+2 pin PCIe (600mm+150mm)3616-18AWGYes
SATA (500mm+110mm+110mm+110mm)2818AWGNo
SATA (520mm+110mm+110mm)2618AWGNo
4-pin Molex (450mm+100mm+100mm+100mm)2818AWGNo
AC Power Cord (1400mm) - C13 coupler1116AWG-

This is the first power supply that we evaluate, with three EPS connectors. As it seems Corsair knows something that we don't or else there wouldn't be so many of these connectors. There are also three cables with six PCIe in total. The RM1000x can have three EPS and six PCIe connectors available at the same time! This can be too much, even for a 1000W PSU. 

The number of peripheral connectors is sky-high, but the distance between the peripheral connectors is too short at 100mm. Ideally, these connectors should be 150mm away from each other. 

It wasn't easy to connect the main ATX cable on our sample because the connectors' pair on this cable is not aligned with the PSU's corresponding modular sockets. We had to twist the cable a bit until the connectors aligned. We contacted Corsair about this, and they informed us that this issue was only with our 1000W review samples, where we got the wrong ATX cable. Please note that the RM1000x uses a different ATX cable from the RM850x and RM750x. 

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)CWT
PCB TypeDouble Sided
Primary Side-
Transient Filter6x Y caps, 2x X caps, 2x CM chokes, 1x MOV
Inrush ProtectionNTC Thermistor SCK203R0 (3 Ohm) & Relay
Bridge Rectifier(s) 2x GBJ2006 (600V, 20A @ 110°C)
APFC MOSFETs 3x Vishay SiHF30N60E (650V, 18A @ 100°C, Rds(on): 0.125Ohm)
APFC Boost Diode 1x On Semiconductor FFSP1065A (650V, 10A @ 152°C)
Bulk Cap(s) 2x Nippon Chemi-Con (400V, 680uF & 470uF each or 1.150uF combined, 2,000h @ 105°C, KMW)
Main Switchers 2x Infineon IPW60R099C6 (650V, 24A @ 100°C, Rds(on): 0.099Ohm)
APFC Controller Champion CM6500UNX & Champion CM03X
Resonant ControllerChampion CU6901VAC
Topology Primary side: APFC, Half-Bridge & LLC converter
Secondary side: Synchronous Rectification & DC-DC converters
Secondary Side-
+12V MOSFETs8x Intenational Rectifier IRFH7004PbF (40V, 164A @ 100°C, Rds(on): 1.4mOhm)
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 Capacitors

Electrolytic: 2x Nippon Chemi-Con (105°C, W), 4x Nippon Chemi-Con (1-5,000h @ 105°C, KZE), 9x Nippon Chemi-Con (4-10,000h @ 105°C, KY), 1x Rubycon (4-10,000h @ @ 105°C, YXJ)
Polymer: 43x 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 Circuit-
Rectifier 1x PS1045L SBR (45V, 10A) & IPS ISD04N65A
Standby PWM ControllerOn-Bright OB5282

The OEM didn't change, so Channel Well Technology (CWT) makes the new RMx units. The platform has several differences from the previous one to offer improved performance and ATX v2.52 compatibility. The major change is the new fan, while the PCB's dimensions remain the same with the older platform. It is nice to see normal dimensions and not a downsized PCB because, in most cases, smaller dimensions bring increased noise output because there is not enough room between the PSU's components affecting airflow and increasing at the same time, operating temperatures. 

Corsair used good capacitors on both primary and secondary sides, and the MOSFETs are of high quality. This is an expensive platform, especially if we take into account the inflated prices in PSU parts. 

The EMI filter is complete with six Y and two X caps, two CM chokes, and an MOV. There is also an NTC thermistor for lower inrush currents, which is supported by a bypass relay. 

The two bridge rectifiers are powerful, able to handle 40 Amps combined! 

The APFC converter uses three Vishay FETs and a single but powerful boost diode. Chemi-Con provides the bulk caps. Combined, they have 1150uF capacity.

The APFC controller is a Champion CM6500UNX IC, supported by a CM03X.

The primary switching FETs are two Infineon IPW60R099C6, configured in a half-bridge topology. The LLC resonant controller is a Champion CU6901VAC

Eight Intenational Rectifier IRFH7004PbF FETs regulate the 12V rails. The FETs are installed on a vertical board, residing right beside the main transformer. 

The VRMs, responsible for generating the minor rails, use four FETs and the common PWM controller is a UPI Semi uP3861P

All electrolytic filtering caps are provided by Japanese manufacturers, Chemi-Con and Rubycon, and are rated at 105 degrees Celsius. Lots of FPCAP polymer caps are also used.

Many polymer caps are installed on the modular board, forming an extra ripple filtering layer. 

The 5VSB circuit uses a pair of SBRs, and the standby PWM controller is an On-Bright OB5282

Soldering quality is not that good. This looks more than a pre-production unit than a mass production one. Most likely, our review samples are among the early ones. 

The cooling fan uses a Magnetic Levitation bearing to last for ages, even under high operating temperatures. This is one of the best fan bearings, if not the best, but expensive and not easy to manufacture. A vertical board holds the fan's controller and the supervisor IC. 

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Contributing Editor

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

  • werther595
    I see in this article that you compare specs with the Superflower Leadex V Pro 1000W. Will there be a review of that unit coming out? Or is there one that I have missed?