Benchmark results
Our testing procedures can be found at this link.
Efficiency
| Load | 10pc | 25pc | 50pc | 75pc | 100pc |
|---|---|---|---|---|---|
| Efficiency | 82.6pc | 88.4pc | 92.2pc | 86.3pc | 87pc |
Looking at the low-load number is instructive. Our latest Haswell-based PC platforms idle at 30W or so (10 per cent load) and the TFX Power 2 is reasonably efficient at that setting. Increasing the load to above 100W provides close to 90 per cent efficiency.
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 | +1.9pc | +2.0pc | +2.6pc |
| 50 per cent | +0.6pc | +0.6pc | +1.5pc |
| 100 per cent | -2pc | -0.5pc | +0.8pc |
Most supplies overvolt with little load and undervolt when stressed. TFX-sized supplies should be no worse off than full-ATX models in terms of regulation as there's enough room to house quality components. The TFX Power 2 Gold is reasonable, if not spectacular, here.
Regulation - cross-load
How about providing uneven loads that stress particular voltage rails? In the first attempt, we've put 20A 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 | -1.8pc | +1.3pc | +2.3pc |
| Cross-load 3.3V/5V focus | -1.6pc | +1pc | +2.5pc |
Hammering one part of the PSU power delivery while using just a small portion of the other can throw cheaper supplies of out kilter. The spread variation is consistent no matter which line is being pushed and pulled.
Ripple
| Line/Load (mv - p-p max) | 3.3V | 5V | 12V |
|---|---|---|---|
| 10 per cent | 10mV | 15mV | 15mV |
| 50 per cent | 30mV | 25mV | 25mV |
| 100 per cent | 35mV | 35mV | 45mV |
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 results are about average for an 80-PLUS Gold-rated supply. Though the 3.3V and 5V numbers are well within specification, we like to see them at half the maximum 50mV rating, ideally.
Temps
| Temperatures | Intake | Exhaust |
|---|---|---|
| 10 per cent | 28°C | 38°C |
| 50 per cent | 36°C | 47°C |
| 100 per cent | 43°C | 52°C |
TFX supplies don't have as much cooling capability as ATX supplies, which are usually outfitted with a 12cm fan. Our sample unit does become quite warm to the touch when under full load from the Chroma harness, but it remained working fine when left for an overnight stress test at 100 per cent capacity.
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 | 700rpm | circa-10cfm | Quiet |
| 50 per cent | 850rpm | circa-15cfm | Quiet |
| 100 per cent | 1,100rpm | circa-30cfm | Noticeable |
We cannot readily distinguish between the fan noise at 10 per cent or 50 per cent loads. Increasing the load quickly above this point has a noticeable effect on noise, with a steady ramp of the fan until 100 per cent is approached. It's difficult to determine in-case noise as each chassis is different, but we'd have no problems in recommending it if average load is around 150W DC.
