The AX1600i is a worthy successor to the legendary AX1500i. Both models are made by Flextronics and feature state-of-the-art technology and a digital platform that provides the best performance money can buy today.

In addition to high efficiency, the AX1600i offers outstanding load regulation, excellent transient response, long hold-up times, and excellent ripple suppression. Despite its large capacity, it maintains quiet operation thanks to its generous fan profile and high-quality FDB fans. Finally, the Corsair Link software allows the user to select between three fan modes: performance, balanced, and quiet.

While the Corsair AX1600i is expensive to acquire, no other PSU comes close to this one when it comes to overall performance. Quite simply, it is the best PSU for gaming (opens in new tab).

Corsair's AX1600i was the first desktop PSU to use such cutting-edge technology, and even now, several years after its release, few PSUs use this technology. In short, the AX1600i uses a totem pole PFC converter utilizing GAN MODFET, which can provide up to 99% efficiency compared to the 96% efficiency levels that state-of-the-art conventional APFC converters can provide.

In addition to the totem pole PFC, the AX1600i has two digital signal controllers (DSCs) to control the circuitry: one microcontroller (MCU) serves as a communication bridge between the system and the PSU, allowing users to perform monitoring tasks as well as several important functions (e.g., fan speed profiles, selection between multiple +12V rails and a single +12V rail, setting OCP limits, etc.). So far, only Wentai has succeeded in bringing a totem-pole PSU to market, but even then it cannot match the performance level and reliability of the AX1600i.

Totem-pole APFC requires a digital controller, and the AX1600i has two controllers, one primary and one secondary, to handle the APFC converters. 12V rails are digitally controlled, while minor rails and 5VSB are analog controllers This reduces cost and design complexity. In addition, fluid dynamic bearings are used for the cooling fans to increase reliability. Given that this PSU is intended for harsh systems, Corsair can also use double ball bearing fans, which are better suited for high temperature operation than FDB fans.

A few more details about the all-pole APFC used by the AX1600i and why it is more efficient: In a conventional APFC converter, when the conduction path is on, the signal must pass through two slow diodes (in a bridge rectifier) and one switch . When the conduction path is off, the signal passes through two low-speed diodes and a fast diode (SBR). In a totem pole PFC, the signal passes through both the MOSFET and the MODFET, so theoretically there is no voltage drop. This is why totem pole PFC can achieve efficiencies up to 99%, while the highest efficiency of the most efficient APFC circuits is around 96%.

The maximum power of 1600W at 12V means that this PSU will handle just about anything. The maximum total power of the minor rails is also as high as 180W. Most modern PSUs are limited to a maximum minor rail power of 100W to 120W.

Plenty of cables and connectors are available, but no 12+4-pin PCIe; hopefully Corsair will keep the AX1600i on the market, make it compatible with ATX v3.0, and add a new PCIe connector.

Turning to performance, load regulation is very tight on all rails and ripple suppression is excellent. The bulk caps have sufficient capacitance to provide long hold-up times even when the PSU is operating at full load, and inrush currents are at very low levels.

Efficiency is high at both normal and light loads, especially the 5VSB rail, and the AX1600i outperforms all other platforms with respect to average efficiency thanks to its totem pole APFC converter. The AX1500i was already an uphill battle for the competition, but the AX1600i is on another level, leaving no doubt as to who is the king of performance.

Transient response is excellent on all rails, with AX1600i dominating the competition, especially on minor rails; on 12V, only the Superflower Leadex platform, which does not use digital circuitry, has a slight lead.

The digital platform allows OCP adjustment at 12V. Minor rails are super strong, OCP is set at 130-136% of nominal power level, overpower protection is at normal levels, and PSUs can deliver over 1900W before shutdown.

The high efficiency levels allow for relaxed fan speed profiles that can be custom-tuned through iCUE software, making the AX1600i one of the best high capacity PSUs available.

We hope that Corsair will work with Flextronics to update the AX1600i to meet all the new ATX v3.0 requirements. This will not be as difficult as with other analog platforms, as the performance and protection features of the PSU can be adjusted through firmware changes, but it will not be an easy task either. When the new GPUs come out, it will be clear whether the PCIe 5.0 connector will be the new default or whether the legacy PCIe connector (6+2 pins) will be extended. Nevertheless, it is a fact that ultimately PCIe 12+4-pin connectors will dominate the market, and all PSUs with capacities above 450W will need to be equipped with PCIe 12+4-pin connectors.

The Corsair AX1600i is still the highest performing PSU available on the market, even years after its launch, and Corsair's initial use of GaN MODFETs and totem pole APFC converters in a desktop PSU was brilliant and the gamble paid off. If any PSU comes close, it would be Be quiet, the Dark Power Pro 1500W, but here Corsair takes the top spot.