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Black rectangular ATX power supply unit with a single 120 mm fan grille and modular cable sockets visible on the front face

Phanteks

Phanteks PH-P850G Amp 850 W power supply

SKU CH-ZJ2F-1KH1Z MPN PH-P850G

A fully modular ATX power supply delivering 850 W with 80 PLUS Gold efficiency, a 120 mm fluid-dynamic-bearing fan, and a compact 140 mm depth

  • Max wattage850 W
  • Modular cablingFull Modular
  • Fan configuration1 × 120 mm
  • Main power connector20+4Pin
  • 12V railsSingle
  • PSU length limit140 mm

Model ATX 80+ Gold (850W)

  • 850 W continuous power from a single +12 V rail rated at 70 A
  • 80 PLUS Gold efficiency reduces waste heat across 100 to 240 V input
  • Fully modular cables keep the build tidy and airflow clear
  • 120 mm fluid-dynamic-bearing fan stays off below 40 % load for silent operation
  • Compact 140 mm depth fits small-form-factor cases while delivering high power density

Compact 850 W ATX supply

The Phanteks Amp PH-P850G is an 850 W ATX12V power supply with full modular cabling and 80 PLUS Gold certification. A single +12 V rail delivers up to 70 A for modern graphics cards and CPUs. The unit measures 140 mm deep, fitting compact cases while maintaining high power density. It operates on 100 to 240 V input at 50 or 60 Hz.

Builders who value cable management

Full modular design lets you connect only the cables your build needs, reducing clutter in small chassis. The 120 mm fluid dynamic bearing fan stays off below 40 percent load for silent idle and light workloads. Systems requiring multiple GPU power connectors are supported with several 6-pin and 8-pin leads. Users needing active PFC or SLI and CrossFire certification should consider other models.

Straightforward installation

Four mounting screws secure the 140 mm deep chassis in any ATX case. Modular connectors are keyed to prevent mis-insertion and the copper plate backpanel ensures solid contact. The most common issue is forgetting to plug the 20+4 pin main and CPU power cables before first boot. Fanless mode engages automatically so no software setup is required.

How it compares

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

Price $93.99
Cheaper than about 70% 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 namePhanteks
Product lineAmp
Model namePH-P850G
Product colorBlack
Product typeATX12 V
Graphics
SLI supportNo
CrossFire supportNo
Ports & slots
Output type+3.3 V@20A, +5 V@20A, +12 V@70A, +5VSB@3A
SATA power connectors8
Power
Max wattage850 W
Modular cablingFull Modular
Main power connector20+4Pin
12V railsSingle
Efficiency certification80 PLUS GOLD Certified
Supply voltage100–240 V
AC input frequency50/60 Hz
Rated input current12–6 A
Power factor correctionNo
Size & build
Product dimensions3.3 in × 5.9 in × 5.5 in
Shipping weight3.00 kg
Package size312 × 183 × 119 mm
Compatibility
PSU length limit140 mm
More details
Fan configuration1 × 120 mm
Mean time between failures>100,000 h

Other versions of this model

2 more in the same range

Questions about this item

What motherboard power connector does the 850 W Amp need?

The PSU uses a standard 20+4 pin ATX12V main connector that plugs into any modern motherboard.

Will the 140 mm depth fit alongside my existing full-length graphics card?

At 140 mm long the unit is compact enough for most mid-tower cases even with a long GPU installed.

How can I confirm the fanless mode is active under light load?

The fan stays completely stopped until the load exceeds 40 % of the 850 W rating, so silence at idle means it is working.

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