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Rectangular ATX power supply unit with matte black finish and gold modular connectors visible on the front face

Seasonic

Seasonic PRIME GX-850 850W 80+ Gold Full Modular power supply

SKU CH-JM23-9GY3Q MPN PRIME GX-850

An 850 W full-modular ATX power supply with 80 Plus Gold efficiency, a single +12 V rail, six PCIe connectors and ten SATA connectors

  • Max wattage850 W
  • Modular cablingFull Modular
  • Fan configuration135 mm Fluid Dynamic Bearing Fan
  • Main power connector20+4Pin
  • 12V railsSingle
  • PCIe power connectors6 × 6+2-Pin

Model ATX Gold (850W)

  • Stable power delivery with .5 % load regulation
  • Clean builds through full modular cabling
  • Lower running costs via 80 PLUS Gold efficiency
  • Silent operation with fanless mode up to 40 % load
  • Long-term reliability backed by 150000 hour MTBF

850 W full-modular ATX supply

The Seasonic PRIME GX-850 delivers 850 W of continuous power through a fully modular cable set. It uses a single +12 V rail rated at 70 A and holds 80 PLUS Gold certification for efficient conversion. The unit fits standard ATX12V and EPS12V bays with a depth of 170 mm.

Hybrid fan control and Japanese capacitors

A 135 mm fluid-dynamic-bearing fan runs in a semi-passive mode that stays off until the load reaches 40 percent. Users can toggle between S2FC and S3FC profiles with a rear switch to match their acoustic targets. Premium Japanese capacitors and micro-tolerance load regulation under .5 percent keep voltages steady.

Six PCIe connectors for multi-GPU builds

The supply provides six 6+2-pin PCIe plugs plus two CPU connectors and ten SATA leads. Gold-plated terminals reduce contact resistance on every cable. This connector count supports multi-GPU configurations without daisy-chaining adapters.

How it compares

Measured against everything we stock in ATX Desktop Power Supplies, at today’s prices. Recalculated every night.

Price $126.99
Cheaper than about 56% of the 10,869 comparable items (median $142.99).
Max wattage 850 W
Typical for this category: the median of 930 items is 850 W.

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Specifications

Product
Brand nameSeaSonic
Product linePRIME Ultra Gold
Model namePRIME GX-850 ( SSR-850GD)
Product typeATX12 V / EPS12 V
Ports & slots
PCIe power connectors6 × 6+2-Pin
SATA power connectors10
Output type+3.3 V@20A, +5 V@20A, +12 V@70A
Connection types1 x Main Power (24/20 pins)
2 x CPU (8/4 pins)
6 x PCIe (8/6 pins)
10 x SATA
5 x Peripheral
1 x Floppy
Power
Max wattage850 W
Modular cablingFull Modular
Main power connector20+4Pin
12V railsSingle
Efficiency certification80 PLUS GOLD Certified
Overvoltage protectionYes
Supply voltage100–240 V
AC input frequency50/60 Hz
Rated input current11–5.5A
Size & build
Product dimensions6.69 in × 5.91 in × 3.39 in
Shipping weight3.63 kg
Package size340 × 208 × 137 mm
Compatibility
PSU length limit170 mm
Environment & compliance
Regulatory approvalscTUVus, TUV, CB, CCC, BSMI, EAC, CE, Energy Star, RoHS, WEEE, ErP Lot 6, REACH
More details
Fan configuration135 mm Fluid Dynamic Bearing Fan
Mean time between failures150,000 h

Other versions of this model

5 more in the same range

Questions about this item

How do I install the full-modular cables, and what is the common mistake?

Connect the 20+4 pin, CPU 8/4 pin, and up to six PCIe 6+2 pin cables only to the ports you need; the step people miss is leaving unused cables in the box instead of plugging every socket.

What maintenance or replacement will this PSU need later?

The 135 mm fluid-dynamic-bearing fan is the only moving part; after many years it may need cleaning or replacement, while the premium Japanese capacitors are rated for long life.

What limit appears first under sustained heavy load?

The single +12 V rail tops out at 70 A, so continuous draws near 850 W will hit the current ceiling before thermal protection engages.

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