Corsair RM850x V2 PSU Review: Smaller And Quieter!

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Teardown & Component Analysis

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General Data
Manufacturer (OEM)CWT
Primary Side
Transient Filter4x Y caps, 2x X caps, 2x CM chokes, 1x MOV
Inrush ProtectionNTC thermistor & relay
Bridge Rectifier(s)2x GBU1506 (600V, 15A @ 100°C)
APFC MOSFETs2x Infineon IPA60R125C6  (650V, 19A @ 100°C, 0.125Ω) 1x SPN5003 FET (for reduced no-load consumption)
APFC Boost Diode1x CREE C3D08060A (600V, 8A @ 152°C)
Hold-up Cap(s)2x Nichicon (400V, 470uF each or 940uF combined, 2000h @ 105°C, GG)
Main Switchers2x Infineon IPA60R190P6  (650V, 12.7A @ 100°C, 0.190Ω)
APFC ControllerChampion CM6500UNX
Switching ControllerChampion CM6901X
Fan ControllerPIC16F1503
TopologyPrimary side: Half-bridge & LLC resonant controller Secondary side: Synchronous rectification & DC-DC converters
Secondary Side
+12V MOSFETs6x International Rectifier IRFH7004TRPBF (40V, 164A @ 100°C, 1.4mΩ)
5V & 3.3VDC-DC Converters: 6x QM3006D (30V, 57A @ 100°C, 5.5mΩ) PWM Controller: Anpec APW7159
Filtering CapacitorsElectrolytics: Nippon Chemi-Con (1-5000 @ 105°C, KZE), Nippon Chemi-Con (4-10,000 @ 105°C, KY) Polymers: FPCAP
Supervisor ICWeltrend WT7502 (OVP, UVP, SCP, PG) & LM393G
Fan ModelNR135L (12V, 0.22A, Rifle Bearing)
5VSB Circuit
RectifierSD04N65A, QM3004D,  LS64 10L45 SBR
Step-Down ConverterAME5268
Standby PWM ControllerOn-Bright OB5269CP

There are a few differences between this PSU and the previous-generation RM850x. For starters, a bypass relay supports the NTC thermistor, allowing for increased efficiency and enhanced inrush current protection. On the primary side, CWT decided to swap out the Vishay FETs for Infineon ones. Both brands are good; however, Infineon products are more popular in high-end PSUs.

The bulk caps are exactly the same as Corsair's older RM850x. There was no reason to change them, since this PSU's hold-up time satisfies the ATX spec's requirements. Both the APFC and LLC resonant controllers are provided by Champion now, whereas the previous-gen RMx units used Infineon controllers.

On the PSU's secondary side, changes are limited to the DC-DC converters. Corsair's updated design uses six QM3006D FETs rather than a combination of four QM3004D and two QM3006D FETs. Moreover, the fan control circuit employs a microcontroller that facilitates fine tuning of the fan's profile.

In general, this is a very good platform with compact dimensions that don't seem to negatively affect performance. Despite the lack of proper heat sinks on the secondary side, Corsair's semi-passive mode lasts a long time. On top of that, its fan profile is relaxed, even under tough conditions. This means that the platform is designed well, even in the face of limited airflow.

Here are some photos showing the PSU’s major parts.

The following video shows the RM850x’s internals.

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Contributing Editor

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

  • parkerygc8
    Sweet, first review of this I've seen. Thanks.
  • leclod
    I didn't go into detail, but I wonder what's the use of that Gold PSU when there's a Seasonic Focus Plus Platinum 750 for a similar price ?
  • Aris_Mp
    Gold, Platinum, it doesn't really matter at this efficiency point. What matters the most, in my opinion at least, is noise output now besides the basic (reliability and overall performance).
  • powernod
    At last some scoring at the review conclusion!! I always considered the lack of score as Tom's greater weakness about their reviews !!