Corsair RM850x 850W ATX 3.1 Fully Modular Power Supply

The Corsair RM850x is an 850-watt ATX power supply with fully modular cabling and a native 12V-2x6 connector. Its stated ATX 3.1 and PCIe 5.1 support suit builds using compatible recent graphics cards, while the 850-watt rating still needs to match the rest of your system.

At a glance

Fully modular cabling lets a builder connect only the cables needed for the selected components.
The listing claims Cybenetics Gold certification and up to 91% efficiency. These are manufacturer claims, not independent measurements here.
The listing describes ATX 3.1 compliance, PCIe 5.1 support and a native 12V-2x6 connector for compatible graphics cards.
Embossed cables with low-profile combs are described as flexible, though customer feedback on cable management is mixed.

Price

$164.99Save 21%

Reference price: ~~$209.99~~

Price checked: Nov 13, 2026

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Pros and cons

Pros

Fully modular cabling can reduce unused cables inside a PC case.
Native 12V-2x6 connection can avoid an adapter for a compatible graphics card.
The 850-watt output and ATX form factor provide a clear starting point for checking system fit.

Technical specifications

15 specifications

Identity and output
Brand	Corsair
Model	RMx
Output wattage	850 watts
Form factor	ATX
Compatible device	Personal Computer
Cable connector type	PCI Express

Standards and cabling
Power supply design	Full Modular
Efficiency claim	Cybenetics Gold-Certified
Power standard claim	ATX 3.1 Compliant
Graphics power support claim	PCIe 5.1 Support
Native connector claim	Native 12V-2x6 Connector

Cooling and installation
Cooling method	Air
Number of fans	1
Dimensions listed	5.8 x 8.6 x 15 centimetres
Weight listed	1.77 kg

What to know before buying

Listing details to confirm

The listing gives dimensions as 5.8 x 8.6 x 15 centimetres in one field and 5.84 x 8.61 x 15.01 cm elsewhere. Confirm case clearance and the exact selected model details before buying. Its model field says RMx, while the product and item model identifiers are presented elsewhere as RM850x and CP-9020270-NA.

Who is it for?

A good fit for

PC builders who want a fully modular ATX power supply and plan to use only the necessary cables.
Builds with a compatible graphics card that uses a 12V-2x6 connection, provided 850 watts meets the system's requirements.

Less suited to

Systems that require a different form factor or more than 850 watts.
Buyers who need independently verified efficiency or noise measurements before choosing a power supply.

Corsair RM850x 850W ATX 3.1 Fully Modular Power Supply · photo 2 — Additional product photo 2

Customer reviews on Amazon

4.8 / 5 · 794 ratings

5 stars89%89%
4 stars6%6%
3 stars2%2%
2 stars2%2%
1 star1%1%

Customer feedback highlights quiet operation, power delivery, reliability, modular design and build quality as strengths, while opinions on cable management vary. That feedback may matter to builders prioritizing a quiet, modular 850-watt unit, but it does not establish measured noise, electrical performance or cable-routing ease. The aggregate ratings skew strongly toward five-star scores, with a smaller spread across lower ratings, so they indicate generally favourable reception but do not explain individual experiences.

Positive themes

Customer feedback describes the power supply as quiet and considers its power delivery and build quality favourable.
The modular design receives positive feedback.

Mixed feedback

Customer opinions on cable management are mixed.

Frequently asked questions

Is this power supply fully modular?

Yes. The listing identifies its design as Full Modular, so the supplied cables are detachable and you can connect only those your build uses.

Does it include a native 12V-2x6 connector?

The product title and feature claims say it has a native 12V-2x6 connector. Check that this connection suits your graphics card and that the 850-watt output fits your complete system.

What are the listed dimensions?

One listing field gives 5.8 x 8.6 x 15 centimetres, while another gives 5.84 x 8.61 x 15.01 cm. The dimensions are inconsistent, so verify clearance against the selected unit before purchase.

What do customers report about it?

The supplied feedback describes quiet operation, power delivery, modular design and build quality positively. Cable-management experiences are mixed. These reports are perceptions, not independent measurements.