Corsair AX1600i

The AX1600i is the worthy successor of the legendary AX1500i. Both units are made by Flextronics, using cutting-edge technology, while offering the best performance that money can buy today thanks to their digital platform. 

Besides being highly efficient, the AX1600i offers outstanding load regulation, excellent transient response, long hold-up time, and excellent ripple suppression. Despite its high capacity, it retains a quiet operation, thanks to the relaxed fan profile and a high-quality FDB fan. Finally, using the Corsair Link software, you’re able to choose between three fan modes: performance, balanced, and quiet, so every user will be able to set the PSU according to their needs. 

You will pay a lot to get your hands on a Corsair AX1600i, but there is nothing else able to meet this PSU eye-to-eye when it comes to overall performance. Quite simply, it’s the best PSU for gaming.

Specifications

The Corsair AX1600i is the first desktop PSU to use such a cutting-edge technology, which even several years after its release, very few PSUs utilize. In short, the AX1600i uses a totem-pole PFC converter, utilizing GAN MODFETs, which can offer up to 99% efficiency compared to the 96% efficiency levels that the most advanced conventional APFC converters can deliver.

Besides the totem-pole PFC, the AX1600i has two Digital Signal Controllers (DSCs) to control its circuits. A single microcontroller (MCU) is the communications bridge between the system and the PSU, allowing users also to control some vital functions of the PSU (for example, the fan speed profile and the selection between multiple and single +12V rails, setting up the OCP limits, etc.) besides monitoring tasks. Up so far, only Wentai managed to push to the market a totem-pole PSU, but still cannot meet the AX1600i’s performance levels and reliability.

The totem-pole APFC requires a digital controller, and the AX1600i has two of these, to handle the APFC converter, the primary and secondary sides. The 12V rail is digitally controlled, while the minor rails and 5VSB use analog controller, to keep the cost and the design’s complexity in control. The build quality is top-notch, and the cooling fan uses a fluid dynamic bearing, for increased reliability. Given that this PSU is for extreme systems, Corsair could also use a double ball-bearing fan, which is more suitable, than FDB fans, for operation under high operating temperatures.

Some more details about the total-pole APFC that the AX1600i uses and why it offers increased efficiency: In a conventional APFC converter, when the conduction path is on, the signal has to pass through two low-speed diodes (of the bridge rectifiers) and one switch. When the conduction path is off, the signal passes from two low-speed diodes and a high-speed diode (SBR). In a totem-pole PFC, the signal passes through a MOSFET and a MODFET in both cases, so we theoretically have no voltage drops. This is why totem-pole PFCs achieve up to 99% efficiency, while the most efficient APFC circuits top out around 96%.

1600W max power at 12V mean that this PSU will handle everything you throw at it. The max combined power on the minor rails is also high, at 180W. Most PSUs nowadays are restricted to 100 to 120W on the minor rails.

Plenty of cables and connectors are provided, but there is no 12+4 pin PCIe. Hopefully, Corsair will keep the AX1600i on the market and make it compatible with ATX v3.0, adding also the new PCIe connector.

Performance

Looking to performance, and load regulation is super-tight on all rails and ripple suppression is excellent. The bulk caps have enough capacity to provide a long hold-up time, even when the PSU operates at full load, and the inrush currents are super-low.

Efficiency is high under both normal and light loads, especially the 5VSB rail. The AX1600i puts to shame all other platforms regarding average efficiency, thanks to its totem-pole APFC converter. The AX1500i was already a difficult opponent for the competition; the AX1600i is on a different level, not leaving any room for doubt about who is the performance king.

Transient response is excellent on all rails, especially the minor ones where the AX1600i smokes the competition. At 12V, only the Super Flower Leadex platform has a small lead, without using any digital circuits.

The digital platform allows for OCP adjustments at 12V. The minor rails are super strong, with OCP set at 130 to 136% of their nominal power levels, and the over power protection is at a normal level, allowing the PSU to deliver more than 1900W before shut down.

The high efficiency levels allow for a relaxed fan speed profile, which can be custom tuned through the iCUE software, making the AX1600i one of the quitest high-capacity PSUs.

Final thoughts

(Image credit: Future)

We hope that Corsair will be able to work things out with Flextronics and update the AX1600i to meet all new ATX v3.0 requirements. This won’t be as hard as in other analogue platforms, because through firmware changes the PSU’s performance and protection features can be adjusted, but it won’t be an easy task, too. Once the new GPUs come out, we will know for sure if the PCIe 5.0 connectors will be the new default or the legacy PCIe connector (6+2 pin) will get a life extension. Still, the fact is that eventually the PCIe 12+4 pin connectors will dominate the market, so all PSUs with 450W and more capacity should have them.

The Corsair AX1600i is the highest performance PSU available on today’s market, even several years after its release. Corsair did well to be the first to adopt GaN MODFETs and the totem-pole APFC converter in a desktop PSU and this gamble paid off. If there were a PSU to get close, it’d be the Be quiet! Dark Power Pro 1500W, but Corsair takes the top spot here.

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