facebook rss twitter

Review: Corsair HX1200i

by Tarinder Sandhu on 10 June 2015, 16:21

Quick Link: HEXUS.net/qacr32

Add to My Vault: x

Running the numbers

Our testing procedures can be found at this link.


Load 10pc 25pc 50pc 75pc 100pc
Efficiency - HX1200i 86.8pc 92.6pc 94.1pc 92.7pc 92.0pc
Efficiency - AX1200i 87.0pc 91.9pc 93.8pc 92.5pc 91.2pc

Platinum-rated supplies should all exhibit excellent efficiencies across a wide load range. It makes sense therefore to see how the newer HXi stacks up against the Flextronics-built, all-digital AXi that's been widely available for almost three years now.

Efficiency is a tad better once we run from 25 per cent to full load. There's very little in it, however, and having 90 per cent-plus across a reasonable load is indicative of a top-quality PSU.


In terms of regulation, we're looking at just how well the supply is able to hold to the various lines. The ATX spec. has a +/- 5 per cent leeway on all but the -12V line.

Line/Load 3.3V 5V 12V
10 per cent - HX1200i +0.9pc +0.6pc +0.6pc
10 per cent - AX1200i +0.8pc +0.3pc +0.5pc
50 per cent - HX1200i +0.6pc +0.6pc +0.5pc
50 per cent - AX1200i +0.1pc +0.3pc +0.5pc
100 per cent - HX1200i -0.6pc -0.4pc -0.6pc
100 per cent - AX1200i -0.4pc -0.3pc -0.4pc

Most supplies overvolt with little load and undervolt when stressed. The HXi isn't quite as excellent as the AXi, most likely due to the latter using digital control, but the minor variances in regulation remain very, very good.

Regulation - cross-load

How about providing uneven loads that stress particular voltage rails? In the first attempt, we've put 90A on the 12V rails, and 1A on the 3.3V and 5V rails. This can actually be somewhat typical for a system heavy on graphics and CPU power. In the second, we've turned the tables and gone for 12A on both the 3.3V and 5V rails - highly unlikely in a real-world environment - and just 2A on the 12V - even more unlikely!

Line/Load 3.3V 5V 12V
Cross-load 12V focus - HX1200i +1.1pc +1.0pc -0.6pc
Cross-load 12V focus - AX1200i +0.7pc +0.7pc -0.4pc
Cross-load 3.3V/5V focus- HX1200i -1.6pc -1.1pc +0.6pc
Cross-load 3.3V/5V focus - AX1200i -1.3pc -0.9pc +0.6pc

Hammering one part of the PSU power delivery while using just a small portion of the other can throw cheaper supplies of out kilter. There's little variation going on here; you're looking at just under two per cent from a best-to-worst-case scenario. Again, the AXi tends to be that tiny bit better.


Line/Load (mv - p-p max) 3.3V 5V 12V
10 per cent - HX1200i 10mV 15mV 15mV
10 per cent - AX1200i 10mV 15mV 15mV
50 per cent - HX1200i 15mV 15mV 20mV
50 per cent - AX1200i 10mV 15mV 20mV
100 per cent - HX1200i 15mV 20mV 25mV
100 per cent - AX1200i 15mV 20mV 20mV

The ATX v2.2 spec states that the maximum permissible ripple is 120mV for the 12V line and 50mV for others.

PSUs convert AC power into DC, but doing so requires the AC waveform to be suppressed. What we're really testing here is the quality of the supply's rectifier and any smoothing capacitors in getting rid of this unwanted up-and-down ripple - the raison d'etre of this supply.

Both are well inside the ATX spec, massively so in most cases, and it's only through a 'scope that you can differentiate the electrical performance of the premium Corsair duo.


Temperatures Intake Exhaust
10 per cent - HX1200i 28°C 36°C
10 per cent - AX1200i 28°C 37°C
50 per cent - HX1200i 33°C 40°C
50 per cent - AX1200i 34°C 39°C
100 per cent - HX1200i 38°C 45°C
100 per cent - AX1200i 37°C 44°C

Platinum-rated efficiency has the ancillary benefit of producing very little heat. Being close to 95 per cent efficient at 50 per cent means the fan doesn't have much work to do in order to keep the unit working at sensible temperatures. Both supplies are silent at 400W.

Fan performance

Temps are good but they mean little in isolation. Obtaining accurate noise readings is near-on impossible when the supply is connected to the Chroma test harness and dual-unit load-tester. We can test the manufacturer's quietness claims in a different way, by using an AMPROBE TMA10A anemometer placed directly over the centre of the PSU. The anemometer records the airflow being pushed/pulled from the PSU's fan. We can use a Voltcraft DT-10L RPM meter to measure the rotational speed of the fan, too.

Load Fan RPM Airflow Noise
10 per cent - HX1200i 0rpm 0cfm Silent
10 per cent - AX1200i 0rpm 0cfm Silent
50 per cent - HX1200i 550rpm 20cfm Very quiet
50 per cent - AX1200i 650rpm 25cfm Very quiet
100 per cent - HX1200i 1,200rpm 65cfm Quiet
100 per cent - AX1200i 1,250rpm 60cfm Quiet

Silent at low loads and remaining quiet when pushed right up to 1,200W in both cases, we believe that you will hear other parts of the system before the noise emitted by the PSU fan.