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Corsair RM850x White PSU Review

Teardown & Component Analysis

Before proceeding with this page we strongly encourage you to 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. Our main tools for disassembling PSUs are a Thermaltronics soldering and rework station and a Hakko FR-300 desoldering gun. Finally, for the identification of tiny parts we use an Andonstar HDMI digital microscope.

General Data
Manufacturer (OEM)CWT
Platform Model-
Primary Side
Transient Filter6x Y caps, 2x X caps, 2x CM chokes, 1x MOV
Inrush ProtectionNTC Thermistor
Bridge Rectifier(s)2x GBJ1510 (700V, 15A @ 100°C)
APFC MOSFETs2x Vishay SiHF22N60E (650V, 13A @ 100°C, 0.18Ω)
APFC Boost Diode1x Power Integrations QH08TZ600 (600V, 8A @ 150°C)
Hold-up Cap(s)2x Nichicon (400V, 470uF each or 940uF combined, 2000h @ 105°C, GG)
Main Switchers2x Vishay SiHG20N50C (560V, 11A @ 100°C, 0.27Ω)
APFC ControllerInfineon ICE3PCS01G - CM03X
Switching ControllerInfineon ICE2HS01G
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, 1.4 mΩ)
5V & 3.3VDC-DC Converters: 4x QM3004D (30V, 40A @ 100°C, 8.5 mΩ) 2x QM3006D (30V, 57A @ 100°C, 5.5 mΩ) PWM Controller: Anpec APW7159
Filtering CapacitorsElectrolytics: Nippon Chemi-Con (1-5000h @ 105°C, KZE), Nippon Chemi-Con (4-10,000h @ 105°C, KY), Nippon Chemi-Con (5-6000h @ 105°C, KZH) Polymers: FPCAP
Supervisor ICWeltrend WT7502 (OVP, UVP, SCP, PG), LM358
Fan ModelNR135L (12V, 0.22A, Rifle Bearing)
5VSB Circuit
RectifierSD04N65A FET, QM3004D FET, MBRU2045CT SBR (45V, 20A @ 125°C)
Standby PWM ControllerOn-Bright OB5269CP

This is the same CWT platform found in all RMx PSUs, including the black RM850x. A half-bridge topology is used on the primary side, along with an LLC resonant converter. On the secondary side, a pair of DC-DC converters generate the minor rails. The +12V rail is generated through six FETs installed on two vertical boards with no heat sinks attached on them. Besides transferring power to the main PCB, a small number of bus bars also cool the +12V FETs.

Corsair's capacitor selection is typical for a good PSU. We find Nippon Chemi-Con KZE and KY electrolytic caps, along with some KZH and a number of Japanese polymer caps provided by FPCAP (Functional Polymer Aluminum Solid Electrolytic Capacitors).

The rifle bearing-based cooling fan spins slowly, so it won't be heard even under stressful conditions.

Finally, the build quality is excellent. An excess of white glue is there to make sure you won't hear any coil whine. It might not look good, but it's surprisingly functional. Since power supplies are rarely opened up, most users won't even know it's there.

The following footage shows the RM850x White's internals.


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  • stairmand
    I've got one of these and wish I had bought a different PSU and paid for cable mods instead. The in line caps are not too big a deal (lets not forget the whole point of the colour and cables IS the aesthetics) but the way the PCIe cables are wired (in a Y config) is terrible and makes it very hard to neatly cable.

    The combes are also relatively poor quality and don't clip together brilliantly especially as there are multiples wires used in a couple of pins.
    Reply
  • vapour
    Looks nice, but seems to behind Seasonic Focus Point and EVGA Supernova G2. Make better psus, Corsair!
    Reply
  • feelingtheblanks
    Hey Aris,

    Is there a possibility to retest one of those Evga Supernova G2 units, like G2 750, in terms of the new hold-up time tests?

    I read your Leadex Gold 550 review, where you find out the hold up time of that unit (and maybe the whole platform) is questionable and not really safe. So that made me think that the rest of the platform and also the Evga units are plagued by the same important mistake.

    I own a G2 750 and after reading that review and some forum threads, I'm a bit worried now.

    Hope you can help.

    Best
    Reply
  • turkey3_scratch
    20451514 said:
    Looks nice, but seems to behind Seasonic Focus Point and EVGA Supernova G2. Make better psus, Corsair!

    RMx have always been better than the G2 because they're quieter.
    Reply
  • Aris_Mp
    Unfortunately I don't have any G2 units any more, to test for hold-up time.
    Reply
  • feelingtheblanks
    20453647 said:
    Unfortunately I don't have any G2 units any more, to test for hold-up time.

    Thanks for the answer Aris,

    Do you think that these units are safe though? G3 850 seems fine on your tests. Are there dramatic differences between G2 750/850 and G3 850 in terms of bulk caps etc...? You have a rough estimation maybe?

    Best


    Reply
  • Aris_Mp
    I believe that the G2s are pretty good units and I would't hesitate to use them. Unfortunately I cannot estimate their hold-up time without testing them (something impossible now since they are EOL).
    Reply
  • turkey3_scratch
    20454054 said:
    20453647 said:
    Unfortunately I don't have any G2 units any more, to test for hold-up time.

    Thanks for the answer Aris,

    Do you think that these units are safe though? G3 850 seems fine on your tests. Are there dramatic differences between G2 750/850 and G3 850 in terms of bulk caps etc...? You have a rough estimation maybe?

    Best


    I looked into it before. The 650 G2 most likely has the problem where it drops the PWR_OK signal after the voltages go out of spec. The 550W should be fine. I'd assume the 750W is perfectly fine also. Not something to worry much about anyway.
    Reply
  • YoAndy
    My previous corsair GS700 fried my motherboard(lasted only 2 years of mild use)..
    Reply
  • turkey3_scratch
    20454749 said:
    My previous corsair GS700 fried my motherboard(lasted only 2 years of mild use)..

    Pretty sure those were some of the most unreliable units in history. RMA rates above 10% I believe.
    Reply