Efficiency

Using the efficiency results from the previous page, we plotted a chart to show the efficiency of the PT-1200FM at low loads and at loads equal to 20% -100% of the PSU's maximum-rated load.



FSP's flagship unit performed superbly with both low and normal loads, leaving behind all other competitive offers. FSP used all the tricks in the book, a dirty one included - the small bulk caps to increase efficiency. The results we obtained prove that they achieved their goal.

Efficiency at Low Loads

In the next tests, we measured the PT-1200FM'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 very high for a 1.2 kW unit. The unit easily cracked the 80% mark with only 60 W, and efficiency exceeded 87% with 100 W. It would have been crazy to even broach the idea of a high capacity unit performing as well with such low loads a few years ago.

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 was very efficient at first, but it failed to crack the 80% mark in the last two tests. Its overall performance was more than decent, but we expected more from such a high-end platform.

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).

Phantom power stayed low, which is as expect from a modern PSU.

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 its 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 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 PT-1200FM is pretty silent for a unit of its capacity. You should look for a PSU with a lower capacity if you need an even quieter unit.