Corsair RMx Series 850 W (2021) Review

Name: Corsair RMx Series 850 W (2021)
Brand: Corsair
Price: 150 USD

crmaris

on Mar 30th, 2021,

in Power Supplies.

Manufacturer: Corsair

Voltage Regulation Stability & Ripple »

Component Analysis

Before reading this page, we strongly suggest a look at this article, which will help you understand the insides of a PSU better.

Corsair RM850x Parts Description
General Data
Manufacturer (OEM)	CWT
PCB Type	Double-sided
Primary Side
Transient Filter	4x Y caps, 2x X caps, 2x CM chokes, 1x MOV
Bridge Rectifier(s)	2x GBU1506 (600 V, 15 A @ 100 °C)
Inrush Current Protection	NTC Thermistor (SCK-037) (3 ohm) & Relay
APFC MOSFETs	2x Vishay SiHF30N60E(650 V, 18 A @ 100 °C, Rds (on): 0.125 ohm)
APFC Boost Diode	1x STMicroelectronics FFSP0865A (650 V, 8 A @ 155 °C)
Bulk Cap(s)	2x Nippon Chemi-Con (400 V, 470 uF each or 940 uF combined, 2,000 h @ 105 °C KMW)
Main Switchers	2x On Semiconductor FCPF190N60E (600 V, 13.1 A @ 100 °C, Rds (on): 0.19 ohm)
APFC Controller	Champion CM6500UNX & Champion CM03X
Switching Controller	Champion CU6901VAC
Topology	Primary side: APFC, half-bridge & LLC converter Secondary side: synchronous rectification & DC-DC converters
Secondary Side
+12 V MOSFETs	6x On Semiconductor NTMFS5C430N (40 V, 131 A @ 100 °C, Rds (on): 1.7 mOhm)
+5 V & +3.3 V	DC-DC Converters: 2x UBIQ QM3054M6 (30 V, 61 A @ 100 °C, Rds (on): 4.8 mOhm) 2x UBIQ QN3107M6N (30 V, 70 A @ 100 °C, Rds (on): 2.6 mOhm) PWM Controllers: UPI Semi uP3861P
Filtering Capacitors	Electrolytic: 7x Nippon Chemi-Con (1–5,000 h @ 105 °C, KZE), 7x Nippon Chemi-Con (4–10,000 h @ 105 °C, KY), 1x Rubycon (4–10,000 h @ 105 °C, YXJ) Polymer:37x FPCAP
Change Over Switch	1x Sync Power SPN3006 MOSFET (30 V, 57 A @ 100 °C, Rds (on): 5.5 mOhm)
Supervisor IC	Weltrend WT7502R (OVP, UVP, SCP, PG)
Fan Controller	Microchip PIC16F1503
Fan Model	Corsair NR140ML (140 mm, 12 V, 0.27 A, magnetic levitation bearing fan)
5VSB Circuit
Rectifier(s)	1x PS1045L SBR (45 V, 10 A) & IPS ISD04N65A
Standby PWM Controller	On-Bright OB5282

The platform is by CWT, and after a quick first glance, it looks the same as the older RM850x platform, but there are several differences. The components CWT used are of high quality, and the same goes for the magnetic levitation bearing fan. Japanese manufacturers provide all the caps, and a great number of polymer caps are used as well. Lastly, since PCB dimensions are regular, there is plenty of space between components, so airflow is unobstructed.

The transient filter has all the necessary components to deal with voltage surges, and suppresses incoming and outgoing EMI emissions.

Large inrush currents are suppressed by an NTC thermistor and bypass relay combination, which does a fine job.

The two bridge rectifiers can handle up to 30 A of current.

The APFC converter's FETs are provided by Vishay, so they are of top quality. The same goes for the boost diode, which is strong enough for the job. Finally, the bulk caps are provided by Chemi-Con and have enough capacity to provide a hold-up time of over 17 ms.

Two On Semiconductor FETs installed in a half-bridge topology are the main FETs.

The APFC controller is the Champion CM6500UNX, and a CM03X IC supports it.

The LLC resonant controller is a Champion CU6901VAC.

The FETs that regulate the +12 V rail are six On Semiconductor NTMFS5C430Ns. They are installed on a vertical board close to the main transformer.

Two DC-DC converters generate the minor rails. They use four UBIQ FETs, and the common PWM controller is a UPI Semi uP3861P.

The electrolytic caps are provided by Chemi-Con and Rubycon, and there are loads of polymer caps by FPCAP, which are much more tolerant to high operating temperatures.

The 5VSB circuit uses a PS1045L SBR on its secondary side, and the standby PWM controller is an On-Bright OB5282 IC. Once the PSU starts, the 5VSB rail takes power from the 5 V rail. This is done through a change-over switch, a Sync Power SPN3006 FET.