Efficiency

Using the efficiency results from the previous page, we plotted a chart showing efficiency of the P1700-MA-EU at low loads and at loads equal to 20% -100% of the PSU's maximum-rated load.



Efficiency is pretty low with low loads, which clearly shows this platform's age as compared to the newer and more advanced ones. Efficiency was high enough with normal loads, though it still didn't match that of other modern high-capacity units. Although PSU technology ages much slower than the technology of other components, like VGAs and CPUs, a platform that has been in production for several years obviously can't compare to contemporary designs in terms of performance.

Efficiency at Low Loads

In the next tests, we measured the P1700-MA-EU'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 over 500 W of capacity). This is important for settings where the PC is in idle mode with Power Saving turned on.

Efficiency with low loads was pretty low. The unit is tuned for higher efficiency at normal loads, so efficiency with less than 100 W is only mediocre at best.

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 very well, with efficiency exceeding 80% in the last two tests. However, we didn't put a full 4 A on the 5VSB rail since we messed up a bit: We initially thought the maximum amperage on this rail to be 3 A, and only after removing it from the test bench did we notice that it was specified for 4 A instead.

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).

Power consumption in standby was well within the ErP Lot 6 2013 directive's range.

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 the 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.