Efficiency

Using the efficiency results from the previous page, we plotted a chart that shows the ZM1000-EBT's efficiency at low loads and loads equal to 20% -100% of the PSU's maximum-rated load.



As you can see in these graphs, Sirfa's HPJ platform cannot compete against other platforms of similar capacity with LLC resonant converters to decrease energy losses and boost efficiency. However, the results are good enough given this unit's price tag.

Efficiency at Low Loads

The next tests measures the ZM1000-EBT's efficiency at loads much lower than 20% of its maximum-rated load (the lowest load the 80 Plus Standard measures). The loads we dialed were 40 W, 60 W, 80 W, and 100 W (for PSUs with a capacity over 500 W). This is important for settings where the PC is in idle mode with Power Saving turned on.

Not top-notch efficiency wise, the results are decent for the price. The only problem here is the fan's high speed at such light loads. Ambient temperature in these tests were between 38°C-39°C, which is apparently enough to make the fan spin at speeds that produce enough noise to be considered annoying.

5VSB Efficiency

The ATX specification states that 5VSB standby supply efficiency should be as high as possible and recommends 50% or higher efficiency with 100 mA of load, 60% or higher with 250 mA of load, and 70% or higher with 1 A or more of load.

We will take four measurements: one at 100, 250, and 1000 mA, each, and one with the full load the 5VSB rail can handle.

The 5VSB rail didn't impress us with its efficiency results. At 4 A maximum current output, it might be strong, and its load regulation is tight enough, but we would have liked a reading close to or above 80%.

Power Consumption in Idle & Standby

In the table below, you will find the power consumption and the rails' voltage values (except for -12V) when the PSU is in idle mode (powered on but without any load on its rails) and the power consumption when the PSU is in standby mode (without any load at 5VSB).

The PSU consumes very little energy in standby, which is indicative of an efficient 5VSB rail, especially at very light loads.

Fan RPM, Delta Temperature & Output Noise

The cooling fan's speed (RPMs) and the delta difference between input and output temperature are illustrated in the following chart. The following results were obtained at 38°C-48°C ambient.



A chart that shows the cooling fan's speed (RPMs) and output noise follows. We measure the fan's noise from one meter away, inside a small custom-made anechoic chamber whose internals are completely covered in specialized soundproofing material (Be Quiet! Noise Absorber Kit). Background noise inside the anechoic chamber was below 20 dBA during testing, and the results were obtained with the PSU operating at 38°C-48°C ambient.



The following graph illustrates the fan's output noise throughout the PSU's entire operating range. The same conditions of the above graph apply to our measurements, but the ambient temperature was in-between 28°C and 30°C.



The PSU wasn't very quiet at even normal ambient temperatures. On the contrary, the fan actually produced a significant amount of noise, 37-40 dBA, with light and moderate loads, and ramped up to 46 dBA with higher loads. This is definitely not a quiet PSU, so those sensitive to noise should look for a different PSU.