Corsair RM750 750 W Review 20

Corsair RM750 750 W Review

Load Regulation, Hold-up Time, Inrush Current, Efficiency & Noise »

Introduction


We would like to thank Corsair for supplying the review sample.


Corsair's plan with the revamped RM line is to offer the same performance levels as with its popular RMx lines at more affordable prices. To achieve this, all RM models come with slightly lower-quality capacitors which will still outlive the ten-year warranty and a more affordable fan that uses a rifle bearing. So instead of the Japanese Nichicon and Chemi-Con caps and bullet-proof NR135L fan the RMx models use, you will find Chinese Elite caps and a Hong-Hua fan in their RM units.



Despite the hardware changes mentioned above, the new RM models score higher than current RMx units in some areas as efficiency levels under ultra-light loads are better and the RM models support the new Modern Standby mode in Windows 10. Depending on the hardware, it usually takes 3–15 seconds for a PC in S3 sleep mode to turn on, while the modern standby function promises to bring this time to just under five seconds. As it seems, thanks to the new standby function, our PCs will be able to wake up as fast as our mobile phones.



In today's review, I am going to take a look at the second-strongest RM model with a maximum capacity of 750 W. The RM750 is fully modular and has two EPS and six PCIe connectors, so you definitely won't be left wanting for connectors. The number of peripheral connectors is sufficient as well, and contrary to the RMx models, no in-cable caps are used for better ripple suppression. As Corsair's PSU R&D director, Mr Jon Gerow, states, extra caps on the cables don't offer notably better ripple suppression. They are mostly used to satisfy strict reviewers (me included). Well, there is a point there indeed as it doesn't matter whether the ripple is 19-20 mV or 9-10 mV, for instance.

That said, this is a race, and the brand or manufacturer offering the best performance should be awarded. Finally, if it were not for weird reviewers (like me) who always ask for more, ripple performance would be considered fine for as long as it below 120 mV at +12V as that is what the ATX spec specifies. While every side of the fence has its points, the good thing is that we can meet somewhere in the middle.

Specifications

Corsair RM750 (2019) Features & Specifications
Max. DC Output750 W
PFCActive PFC
EfficiencyETA-A & 80 PLUS Gold
NoiseLAMBDA-A (20-25 dB[A])
ModularYes (fully)
Intel C6/C7 Power State SupportYes
Operating Temperature0 °C - 50 °C
ProtectionsOver Voltage Protection
Under Voltage Protection
Over Power Protection
Over Temperature Protection
Over Current Protection
Short Circuit Protection
Cooling140 mm rifle bearing fan (HA1425M12F-Z)
Semi-passive OperationYes (not selectable)
Dimensions152 mm (W) x 87 mm (H) x 162 mm (D)
Weight1.61 kg (3.55 lb)
ComplianceATX12V v2.31, EPS 2.92
Warranty10 Years
Price at Time of review (excl. VAT)$129.99



Corsair RM750 (2019) Power Specs
Rail3.3 V5 V12 V5 VSB-12 V
Max. Power20 A20 A62.5 A3 A0.3 A
150 W750 W15 W3.6 W
Total Max. Power750 W



Cables and Connectors

Modular Cables
DescriptionCable CountConnector Count (Total)GaugeIn Cable Capacitors
ATX connector 20+4 pin (610 mm)1118-20AWGNo
4+4 pin EPS12V (650 mm)2218AWGNo
6+2 pin PCIe (600 mm+150 mm) 3616-18AWGNo
SATA (450 mm+110 mm+110 mm+110 mm)1318AWGNo
SATA (500 mm+100 mm+100 mm)2618AWGNo
4 pin Molex (450 mm+100 mm+100 mm+100 mm)1418AWGNo
AC Power Cord (1420 mm) - C13 coupler1116AWG-

All cables are long enough, but the distance between the peripheral connectors is short at only 100–110 mm. It should at least be 150 mm, especially on the 4-pin Molex connectors.



Component Analysis

Corsair RM750 Parts Description
General Data
Manufacturer (OEM)CWT
PCB TypeDouble-sided
Primary Side
Transient Filter4x Y caps, 2x X caps, 2x CM chokes, 1x MOV
Bridge Rectifier(s)2x GBU1506(600 V, 15 A @ 100 °C)
Inrush Current ProtectionNTC thermistor & relay
APFC MOSFETs2x Infineon IPA60R190P6(650 V, 12.7 A @ 100 °C, 0.19 Ohm)
APFC Boost Diode1x Power Integrations QH08TZ600 (600 V, 8 A @ 95 °C)
Hold-up Cap(s)2x Su'scon  (400 V, 330 uF each or 660 uF combined, 2,000 h @ 105 °C LZ)
Main Switchers2x Infineon IPA60R190P6 (650 V, 12.7 A @ 100 °C, 0.19 Ohm)
APFC ControllerChampion CM6500UNX & CM03X Green PFC Controller
Switching ControllerChampion CU6901V 
TopologyPrimary side: Half-bridge & LLC converter
Secondary side: Synchronous rectification & DC-DC converters
Secondary Side
+12V6x International Rectifier IRFH7004PBF (40 V, 100 A @ 25 °C, 1.4 mOhm)
5V & 3.3VDC-DC converters: 2x UBIQ QM3054M6 (30 V, 61 A @ 100 °C, 4.8 mOhm) & 2x UBIQ QN3107M6N (30 V, 70 A @ 100 °C, 2.6 mOhm)
PWM Controller(s): uPI SEMI uP3861P
Filtering CapacitorsElectrolytics: 7x Elite (2 - 5,000 h @ 105 °C, EK), 1x Elite (4 - 10,000 h @ 105 °C, EY), 1x Elite (2,000 h @ 105°C, PF), 2x Su'scon (2 - 5,000 h @ 105 °C, MF), 3x Su'scon (4 - 10,000 h @ 105°C, HG),
Polymers: Suncon, Elite, NIC
Supervisor ICWeltrend WT7502 (OVP, UVP, SCP, PG) & LM393G
Fan ControllerMicrochip PIC16F1503
Fan ModelHong Hua HA1425M12F-Z (140 mm, 12 V, 0.36 A, Rifle Bearing Fan)
5VSB Circuit
Rectifiers1x Unisonic Technologies 4N65L FET (650 V, 4 A @ 25 °C, 2.5 Ohm)
Standby PWM ControllerOn - Bright OB5282


The major differences with the RM750x (2018) are the different capacitors on the primary and secondary sides, Hong Hua fan, and new Champion resonant controller that supports burst operations with ultra-light loads for a major efficiency boost. Finally, the DC-DC converters use different FETs and a new PWM controller.


On the primary side, a half-bridge topology is utilized, along with an LLC resonant converter. The bulk caps are by Su'scon, and their combined capacity is lower than with the RM750x (660 uF vs. 860 uF).


Mostly Elite caps are used for ripple filtering on the secondary side, along with a small number of Su'scons. Besides electrolytic caps, a number of polymers are installed as well.


The DC-DC converters that generate the minor rails.


Polymer caps for extra ripple filtering and bus bars for lower losses on power transfers.


Soldering quality is good.


The Hong Hua fan with the rifle bearing. These fans are pretty good and don't cost a fortune, which is why most brands and manufacturers prefer them over more expensive brands (Sanyo Denki, Delta, Protechnic Electric, etc.) For speed control, Corsair uses a Microchip PIC16F1503 as it allows for precise control.
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