Corsair HX1200i ATX 3.1 power supply review

Corsair has long positioned itself as a premium player in the PC component market, with a broad portfolio that includes everything from memory modules to complete systems. Their power supply lineup has been respected for quality and performance, with the HX series representing their near-flagship offerings that rival their own AX series at significantly lower prices.

In this review, we examine the Corsair HX1200i to find out whether this updated version, now featuring ATX 3.1 compliance, belongs among the best power supplies on our list. This high-performance unit offers 1200W of power, a digital interface for monitoring and control, and a semi-passive cooling system, targeting enthusiasts with demanding multi-GPU setups and high-end CPUs. With system builders becoming more price-conscious, the question becomes whether the HX1200i can justify its premium positioning through genuine performance advantages or if it relies primarily on brand cachet.

Specifications and Design

In the Box

The Corsair HX1200i ships in a predictably oversized box featuring Corsair's recognizable yellow and black aesthetic. The packaging demonstrates environmental awareness with minimal plastic, instead utilizing a protective nylon pouch and paper inserts to secure the unit during transport.

The contents reveal a small disappointment: a surprisingly Spartan accessory bundle that feels inadequate at this price point. Despite the premium character of the PSU, buyers receive just the bare essentials mounting screws, a basic AC power cable, and a token handful of cable ties. This minimalist approach stands in stark contrast to competitors, who include comprehensive accessory packages with premium extras like Velcro straps, storage bags, and test adapters. The inclusion of at least a few cable straps would go a long way.

The all-black, individually sleeved cables with pre-installed cable combs on the ATX and PCIe cables are admittedly high quality and visually appealing. The unit includes two 12V-2x6 connectors for PCIe 5.0 GPUs, though each requires two 8-pin PCIe connectors on the PSU side. This configuration splits the current draw from one dense connector to two larger ones, making it arguably more reliable and the design more flexible, as the EPS/PCIe cables also use the same connectors. A unique addition is the internal USB connector that allows the PSU to interface with a motherboard header for monitoring through Corsair's iCUE software.

External Appearance

The Corsair HX1200i presents an aesthetic that balances visual interest with professional restraint. At 200mm in length, the unit extends significantly beyond standard ATX dimensions, requiring careful consideration of case compatibility and internal clearances during system planning.

The chassis features reasonably attractive satin black paint with decorative stickers and chamfered edges that add visual interest without becoming gaudy. The integrated fan guard incorporates a distinctive triangular pattern that repeats in denser form at the rear of the unit, providing visual cohesion. The top side is partially covered by a sticker displaying electrical certifications and specifications.

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The rear panel contains the standard AC receptacle and power switch, while the front houses the modular connection interface with subtle legends to aid installation. There are nine 8-pin connectors for PCIe and EPS cables. It must be noted that not all of the included cables can be connected simultaneously.

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Internal Design

Cooling duties fall to a Corsair NR140P 140mm fan featuring a fluid-dynamic bearing that balances acoustic performance with operational longevity. With a maximum speed of 1800 RPM, the fan operates conservatively for a unit of this capacity, reflecting confidence in the underlying thermal design and efficiency.

Unlike many power supplies marketed under brand names but manufactured by third parties with minimal input, Corsair maintains significant control over design aspects while partnering with Channel-Well Technology (CWT) for manufacturing. The HX1200i represents a rather subtle upgrade to the previous platform, specifically modified to meet ATX 3.1 requirements.

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The electrical architecture begins with comprehensive input filtering, incorporating six Y capacitors, three X capacitors, and two filtering inductors for superior EMI suppression. Dual rectifying bridges mounted on the primary heatsink handle the initial power conversion stage efficiently.

The APFC circuit employs two Infineon 60R099P6 MOSFETs and companion diodes as active components, sharing heatsink space with the rectifying bridges. This digitally controlled array works alongside two encased inductors and three quality capacitors (one 560μF from Nippon Chemi-Con and two 470μF from Rubycon) to optimize power factor correction.

Primary inversion occurs through four Alpha & Omega 29S50 MOSFETs arranged in a full-bridge LLC configuration, mounted on a dedicated heatsink adjacent to the main transformers. The secondary stage utilizes eight Vishay R626 MOSFETs on a vertical daughterboard to generate the primary 12V output, while separate DC-to-DC circuits on another vertical board produce the 3.3V and 5V rails.

The secondary side capacitors, both polymer and electrolytic, come exclusively from premium Japanese manufacturers (Nippon Chemi-Con, Nichicon, and Rubycon), reflecting a no-compromise approach to component selection that promises excellent longevity and performance stability. Component selection is admittedly excellent, featuring top-tier Japanese manufacturers throughout, though this quality should be expected at this price point rather than considered exceptional.

Cold Test Results

Cold Test Results (25°C Ambient)

For testing the power supplies, we use high precision electronic loads with a maximum power draw of 2700 Watts, a Rigol DS5042M 40 MHz oscilloscope, an Extech 380803 power analyzer, two high precision UNI-T UT-325 digital thermometers, an Extech HD600 SPL meter, a self-designed hotbox, and various other bits and parts.

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Under standard conditions, the Corsair HX1200i demonstrated excellent efficiency, earning a Platinum certification from Cybenetics for both AC input voltages. The unit achieved an average nominal load efficiency of 91.9% at 115 VAC and 93.0% at 230 VAC. The efficiency curve is fairly well-balanced, peaking at around 40% load and maintaining impressive levels throughout the operating range. Even at very low loads, the HX1200i maintained excellent efficiency, showcasing the strengths of its design.

The fan remains completely inactive until the load exceeds 600 watts, allowing for silent operation under moderate power conditions. When running, the fan maintains low speeds even at maximum load, creating a quiet operation profile. The thermal performance during cold testing is very good, with internal temperatures remaining remarkably low despite the considerable power output. Power users can also adjust fan’s default cooling profile via the iCUE app.

Hot Test Results

Hot Test Results (~45°C Ambient)

When subjected to elevated ambient temperatures, the Corsair HX1200i behavior changes significantly compared to cold conditions. The unit achieved an average nominal load efficiency of 90.3% at 115 VAC and 92.2% at 230 VAC, reflecting an acceptable but measurable decrease from cold testing results. Regardless, the efficiency shows very little degradation at heavy loads, suggesting no thermal stress even under challenging conditions.

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The fan behavior also changes significantly under high-temperature conditions, activating at a much lower threshold of around 300 watts. Despite this earlier activation, the fan speed increases conservatively, reaching maximum speed only at 100% load. Internal temperatures remain relatively low for a unit of this power rating, demonstrating the excellent thermal design and component selection.

PSU Quality and Bottom Line

Power Supply Quality

Electrical performance is the HX1200i's strongest suit, with brilliant figures across all metrics. The 12V rail maintains 0.7% regulation, while the 5V and 3.3V rails hold at 0.8% and 0.4% respectively, which are impressive figures for a high-wattage unit, even of such a tier. Ripple suppression is even better, with maximum ripple levels of 36 mV on the 12V rail and 22 mV on both minor rails, indicating superior filtering and excellent overall electrical performance.

During our thorough assessment, we evaluate the essential protection features of every power supply unit we review, including Over Current Protection (OCP), Over Voltage Protection (OVP), Over Power Protection (OPP), and Short Circuit Protection (SCP). Protection features are robust, with Over Current Protection (OCP) thresholds set at 116% for the 12V rail and higher at 134% and 132% for the 3.3V and 5V rails respectively. The Over Power Protection (OPP) engages at 118% during hot testing, providing an appropriate safety margin.

Bottom Line

The Corsair HX1200i ATX 3.1 represents a thoughtful balance between advanced features and reliable performance for users requiring substantial power capacity. While its $310 retail price positions it firmly in the premium segment, the combination of exceptional electrical performance, digital monitoring capabilities, and high-quality construction offers genuine value for demanding system configurations. CWT's manufacturing expertise, combined with Corsair's design modifications, has resulted in a power supply with exemplary performance characteristics across the board.

The external design balances aesthetics with functionality, made for sophisticated builds with its all-black, individually sleeved cables providing excellent flexibility for cable management. The inclusion of two PCIe 5.1 12V-2x6 pin connectors is a boon for PC builders wanting to power top-tier gaming systems. However, the physical dimensions require careful planning, with the 200mm chassis length potentially limiting compatibility with some cases.

In terms of overall performance, the HX1200i excels in efficiency, comfortably meeting the Cybenetics Platinum certification requirements across various testing conditions. The unit achieves impressive nominal load efficiency that remains relatively stable throughout its operating range and shows minimal degradation under high-temperature conditions, demonstrating excellent resilience and stability. The electrical performance is equally impressive, with tight voltage regulation and minimal ripple across all rails, and protection features triggering at appropriate thresholds. Thermally, the HX1200i impresses with its ability to maintain low internal temperatures even at high power outputs. The cooling system is intelligently designed, keeping the unit silent under moderate loads and ramping up fan speed only when necessary at high power draws.

The Corsair HX1200i represents a reasonable choice for system builders requiring substantial power with premium electrical performance and advanced features. Its $310 retail price is certainly high but justifiable given its performance characteristics, digital interface, and ATX 3.1 compliance with dual 12V-2x6 connectors. For most system builders, however, alternatives offer better value without significant compromises.

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