What's the Difference Between an HXi and AXi Series Power Supply?

By Dustin Sklavos, on January 27, 2015

The recent launch of the 80 Plus Platinum rated HXi series power supplies coupled with the impending launch of the 1200W HX1200i power supply may leave some end users wondering whether they should go with an HXi series unit or step up to the incumbent AXi series. If your power target is 1000W, then the decision is clear – you go for the HX1000i – but at the other points, things may be a little foggier.

So what’s the difference between HXi and AXi? What merits the AXi series’ higher price tags? Both lines use all Japanese electrolytic capacitors, feature modular cabling, are Corsair Link-enabled, and have Zero RPM modes for fanless operation at low loads. They’re both rated for 80 Plus Platinum efficiency at 50°C. Still, there are a few important differences.

The first and most basic one is dimension.

 

HXi Depth

AXi Depth

 

HX750i

180mm

160mm

AX760i

HX850i

180mm

160mm

AX860i

HX1000i

180mm

N/A

-

HX1200i

200mm

200mm

AX1200i

A difference in depth can seem minor, but for our recent Yamamura build, the 180mm depth of the HX1000i would have prevented us from installing a radiator in the bottom of the 750D. Switching to an AX860i gave us the clearance we needed.

The second major difference is architectural: the AXi series feature fully digital power regulation. While the HXi series is no slouch, the AXi’s power regulation is slightly cleaner. More than that, because the AXi’s power regulation is handled by a DSP (digital signal processor), an AXi power supply will be vastly more user-configurable in Corsair Link.

The AXi allows for extremely detailed monitoring of voltage, amperage, and efficiency, with amperage in particular monitored on a per-cable, per-rail basis. An AXi PSU allows the end user to configure Over-Current Protection trip points manually for the +12V rails and configure the power supply for virtual single or multiple +12V rail operation.  By default, the AXi ships set to multiple +12V rail, so if a single +12V rail is desired, it is necessary to go into Link and uncheck all of the boxes to disable OCP on the +12V rails.

While the AXi series enjoys digital power regulation, the HXi remains a more traditional, time-tested analog solution. Regulation is still extremely tight but can’t quite reach the precision afforded by the DSPs in the AXi units. The DSP is replaced instead by a DAC (digital-to-analog converter) to enable Corsair Link functionality.

Corsair Link monitoring and control is also more limited on the HXi. We retain monitoring of power supply efficiency, temperature, and fan speed. We can also monitor voltage and amperage on the 12V, 5.5V, and 3V rails. The monitoring is more basic, though; while the AXi can monitor specific draws (24-pin motherboard cable, peripherals, individual PCIe rails), the HXi only gives a broad monitoring of 12V draw.

While we can’t configure OCP points on a per +12V rail basis like we can in the AXi, we can still toggle single and multiple +12V rail operation on the HXi.  Like with the AXi series of power supplies, the HXi ships as a multiple +12V rail power supply by default.

What the HXi has in spades over the AXi is price. If you can live without the extra bells and whistles the AXi series bring to the table, you can save a decent chunk of change moving to the HXi. It’s still backed by our 7-year warranty and you’re still getting one of the best, most efficient, quietest analog power supplies on the market. The HXi and AXi both feature Corsair engineering in and out, engineering you can only get from us.


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