9 - Load testing the PSU

We monitored the primary voltages in both IDLE and LOAD (fully utilized) modes. We noted down the lowest and highest value we see and that is the fluctuation. If a PSU is unstable we'd see much more fluctuation, differences and discrepancies which can result in system instability.

Now look at the chart, the two lines show both the idle or Load state of a specific voltage rail, the blue one the lowest voltage dip measured, the red one the highest fluctuation. A 5% fluctuation is acceptable and falls with ATX design specification, so 12 Volts should remain between 11.4 - 12.6 volts. The PSU when utilized stays away from that though all 12V rails where showing roughly 12.17 volts in idle, perfect. But other than that, there's just no fluctuation when you compare the upper and lower voltage distribution.

The Power Supply is stable, did we expect any less ? During the load test  several times I felt (doing it manual with your hand is often practical) to see if the PSU was warm, it remained cold at all times. It feels like it's hardly doing anything at all.

Very notable is this; with a wattage meter we noticed that wattage did not peak over 500 Watts where other PSU's did have much higher peak loads. Now please remember what I told you about power efficiency. This PSU's efficiency is really good and it's showing. We estimate between 80% and 85% efficiency which is on par with the specification.

Some facts:

• Did you know that even with the PSU switch OFF, the PSU still consumes 15 Watt
• Did you know that with the PC off, yet the PSU switch on, this PC still consumed 46 Watt
• In Idle this overclocked system consumes 239 Watt
• The maximum peak we measured was 415 Watt

Definitely a negative - with the PC powered down the PSU still still uses near 45 Watts which is odd. It likely has to do with the integrated USB HUB empowering the Mobile port with juice.

The fact that it remains stone cold at a full PC Power draw we peaked at 412 Watt, which tells me that it can easily cope with the load and that it's energy efficient.

Let's have a look at sound ... ehm, yeah, that's right.

Sound levels (dBA)

As usual we grabbed our dBa meter, enabled the PSU by hot-wiring it and started to listen if it made any significant noise. Short and simple it's really silent. With merely the PSU hotwired and no other electrical devices activated in a closed room we measured a dBA level of roughly 28 dBA. Yes correct ... not even 29 DBa !

The human hearing system has different sensitivities at different frequencies. This means that the perception of noise is not at all equal at every frequency. Noise with significant measured levels (in dB) at high or low frequencies will not be as annoying as it would be when its energy is concentrated in the middle frequencies. In other words, the measured noise levels in dB will not reflect the actual human perception of the loudness of the noise. That's why we measure the dBa level. A specific circuit is added to the sound level meter to correct its reading in regard to this concept. This reading is the noise level in dBA. The letter A is added to indicate the correction that was made in the measurement.

All in all, extremely silent and thus highly recommended to any of the audiophiles that like silence (yours truly included). As always we measure ~75 CM away from the product (usually the distance between you and a desktop computer).

Quite honestly the Power Supply unit hotwired and activated, it is among the most silent PSUs we've ever tested. Very recommendable.