We would like to thank Corsair for supplying the review sample.
Corsair’s top-of-the-line series, AXi, so far includes three members with 760 W, 860 W and 1200 W capacity. Ask us and Corsair should probably add a unit with less capacity to satisfy users who need a top-notch PSU for a small- or mid-level system, but they instead decided to break every barrier in terms of cost and technology to offer an incredibly strong unit that is also the first high capacity PSU to meet the tough 80 Plus Titanium certification. For all of you who aren't aware: It is much easier for a small PSU to achieve high efficiency at full load and below because energy losses increase exponentially as the load increases. The power losses a 1.5 kW monster will suffer at full load due to even the slightest bit of resistance in its circuits can easily prevent it from meeting these strict Titanium or Platinum requirements. However, such hurdles become easier to master with digital control, and not only in terms of efficiency, but also when it comes to voltage regulation and ripple suppression.
The AX1200i was already the best unit we have tested so far, registering exceptional performance in all areas, so the AX1500i has quite tough standards to meet and exceed. On paper, it does look as though Corsair and Flextronics managed to further improve the digital platform by squeezing even more performance out of it. Corsair speaks of up to 94% efficiency, which allows for 1500 watts of power with even 115 V (15 Amp) circuits. Such numbers are not to be taken lightly since a regular US outlet allows for up to about 1725 watts of power draw, which means that a 1.5 kW PSU should have no less than 87% efficiency at full load and under all conditions. Anything less would overload the circuit and trigger its breaker. The situation isn't as dire in the EU since 230 VAC has a typical (15 A) EU outlet deliver up to 3450 W of power.
The AX1500i features a fully modular cabling design and an FDB fan, and its digital circuits allow you to monitor and control various functions through the Corsair Link software. You can also exploit a semi-passive operation Corsair dubbed Zero RPM Fan mode with low and medium loads, which drastically reduces output noise. The single +12V rail can also easily be broken up into multiple +12V rails through the software, a safety measure many users will appreciate.