Our Chroma load-testing procedures can be found at this link.
We're clearly not going to see the 90%-plus rating that's achieved by premium supplies; Xilence, however, does a good job of keeping above 80 per cent across our wide range of loads.
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.
|10 per cent||+0.8%||+1.3%||+1.5%|
|50 per cent||-0.4%||+0.2%||+0.4%|
|100 per cent||-2.0%||-1.3%||-1.4%|
Having looked at PSUs in detail for a number of years, manufacturing quality has improved such that very few supplies do poorly here. Looking a best-to-worse-case scenario, overall fluctuation is less than three per cent.
Regulation - cross-load
How about providing uneven loads that stress particular voltage rails? In the first attempt, we've put 35A 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.
|Cross-load 12V focus||+1.5%||+1.7%||-1.4%|
|Cross-load 3.3V/5V focus||-3%||-1.6%||+2.2%|
Hammering one part of the PSU power delivery while using just a small portion of the other can throw cheaper supplies out of kilter. Now we're pushing the supply into difficult waters. We'd be happy with an overall variation of less than five per cent across each line; the worst-case scenario is on the 3.3V rail.
|Line/Load (mv - p-p max)||3.3V||5V||12V|
|10 per cent||10mV||10mV||20mV|
|50 per cent||15mV||25mV||35mV|
|100 per cent||25mV||35mV||50mV|
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. Performance is comfortably within the limits of the specification.
|10 per cent||30°C||38°C|
|50 per cent||35°C||45°C|
|100 per cent||37°C||49°C|
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.
|10 per cent||700rpm||circa-20cfm||Very quiet|
|50 per cent||1,000rpm||circa-35cfm||Noticeable|
|100 per cent||1,500rpm||circa-70cfm||Very noticeable|
The Evercool fan isn't noticeable until the PSU is forced to run at over half the rated capacity. Should you push it that far, which would happen in most under-load situations, the fan can be heard quite clearly.