Efficiency

Using the efficiency results from the previous page, we plotted a chart showing efficiency of the Straight Power 10 CM 800 W at low loads and at loads equal to 20% -100% of the PSU's maximum-rated load.



Good but not among the best we have seen, efficiency at low and normal loads placed the unit into the middle of the pack. In these charts, PSUs utilizing LLC converters dominate, but such converters often cause coil whine and require more components, which also increases how much a unit costs.

Efficiency at Low Loads

In the next tests, we measured the efficiency of the Straight Power 10 CM 800 W 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 over 500 W of capacity). This is important for settings where the PC is in idle mode with Power Saving turned on.

The fan barely spun with low loads, which kept noise to a minimum. Overall efficiency was also good considering the PSU's relatively high maximum power output figure.

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 performed decently, but we would like to see its efficiency in the last two tests encroach on or surpass the 80% mark.

Power Consumption in Idle & Standby

In the table below, you will find the power consumption and the voltage values of all rails (except -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).

As expected, vampire power is very low.

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-45°C ambient.



A chart that shows the cooling fan's speed (RPMs) and the output noise follows. We measure the fan's noise from 1 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-45°C ambient.



The following graph illustrates the fan's output noise throughout the entire operating range of the PSU. 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's fan is inaudible with light- to mid-level loads; however, it becomes noisy enough to probably annoy most of you with loads at or above 650W. No doubt, this is a high RPM fan, so it can, although it uses a Fluid Dynamic Bearing, be noisy once internal temperatures increase.