Testing results
Our testing procedures can be found at this link.
Efficiency
| Load | 10pc | 25pc | 50pc | 75pc | 100pc |
|---|---|---|---|---|---|
| Efficiency | 83.5pc | 90.6pc | 92.8pc | 90.9pc | 90.5pc |
Efficiency, as expected, is excellent from 25 per cent to 100 per cent load. The numbers are fairly close to the Flextronics-based AX860i's.
Regulation
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 | +0.8pc | +0.9pc | +1.0pc |
| 50 per cent | +0.6pc | +0.5pc | +0.6pc |
| 100 per cent | -0.4pc | -0.1pc | -0.4pc |
Most supplies overvolt with little load and undervolt when stressed. The ATX specification is simply too lenient to trip-up any high-quality supply. Underscoring this, we've not had a single PSU fail the ATX specification thus far, though do understand that any PSU with a total leeway of below two per cent is considered to be premium quality.
Regulation - cross-load
How about providing uneven loads that stress particular voltage rails? In the first attempt, we've put 60A 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 | +0.9pc | +1.0pc | -0.6pc |
| Cross-load 3.3V/5V focus | -1.4pc | -0.7pc | +0.8pc |
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 over two per cent from a best-to-worst-case scenario. Following on from the regular tests, anything below three per cent is premium.
Ripple
| Line/Load (mv - p-p max) | 3.3V | 5V | 12V |
|---|---|---|---|
| 10 per cent | 10mV | 15mV | 15mV |
| 50 per cent | 15mV | 15mV | 20mV |
| 100 per cent | 20mV | 20mV | 30mV |
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.
Suppression of ripple isn't quite as tight as the AX860i's, mind, but the 30mV performance at 12V keeps the AX760 in the premium category.
Temps
| Temperatures | Intake | Exhaust |
|---|---|---|
| 10 per cent | 28°C | 35°C |
| 50 per cent | 34°C | 39°C |
| 100 per cent | 39°C | 45°C |
Set to hybrid mode and thus not activating the fan until load is increased above 50 per cent, overall temperatures are good. The supply is rated to provide continuous power at an ambient 50°C, which, we note, is higher than temperature we test at.
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 | 0rpm | 0cfm | Silent |
| 50 per cent | 0rpm | 0cfm | Silent |
| 100 per cent | 1,150rpm | 45.0cfm | Quiet |
Here is where it becomes interesting; the supply is silent at 10 per cent load, as you would expect, but does occasionally kick-in at around 400W during testing. This circa-50 per cent load figure is lower than the 70 per cent fanless touted by Corsair, obviously, but could well be down to the rise in ambient temperature during testing.
As usual, we also installed it onto our high-end PC, equipped with a GeForce GTX 680, and ran through a few games. The PSU fan remains off, and it's therefore unlikely to be required in the majority of mainstream builds.
