Testing Results
Our Chroma load-testing procedures can be found at this link.
Efficiency
| Load | 10% | 25% | 50% | 75% | 100% |
|---|---|---|---|---|---|
| Efficiency | 82.1% | 90.3% | 93% | 91.4% | 90.9% |
Efficiency starts off a little lower than we'd like at 10 per cent load, which is fairly typical of a modern PC idling or running basic tasks. Matters improve as we scale the load ladder, and getting over 90 per cent efficiency at full load is above average.
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 | +0.7% | +1.3% | +1.4% |
| 50 per cent | +0.4% | +0.6% | +0.6% |
| 100 per cent | -1.7% | -0.1% | -0.3% |
If efficiency is good at high loads, regulation is simply excellent, with the CWT platform doing well.
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 10A 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 | +1.8% | +1.2% | -0.8% |
| Cross-load 3.3V/5V focus | -1.3% | -1.2% | +1.2% |
It's becoming increasingly difficult to find bad power supplies; the OEMs have all upped their game enough such that no one stands out - for good reasons or bad. Buying a supply with a quality underpinning from, say, CWT, Seasonic, Delta, et al, is easy.
Ripple
| Line/Load (mv - p-p max) | 3.3V | 5V | 12V |
|---|---|---|---|
| 10 per cent | 12mV | 13mV | 12mV |
| 50 per cent | 18mV | 25mV | 21mV |
| 100 per cent | 24mV | 31mV | 33mV |
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. Another very good showing here, matching what's on offer from the latest generation of Seasonic units.
Temps
| Temperatures | Intake | Exhaust |
|---|---|---|
| 10 per cent | 31°C | 39°C |
| 50 per cent | 35°C | 44°C |
| 100 per cent | 39°C | 47°C |
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 | 400rpm | circa-15cfm | Very quiet |
| 50 per cent | 500rpm | circa-20cfm | Very quiet |
| 100 per cent | 1,450rpm | circa-65cfm | Noticeable |
The fan, being larger than many, means it can produce decent airflow with low-ish RPMs.
Dialled to a mid-load of 250W and therefore representing the kind of AC power used for a reasonable gaming system, the fan remains very quiet.
