Efficiency

Using the efficiency results from the previous page, we plotted a chart showing efficiency of the Leadex Gold 750 W at low loads and at loads equal to 20% -110% of the PSU's maximum-rated load.



The Leadex Gold unit did well with both low and normal loads and its efficiency is, as you can see, very close to that of the older SF Platinum platform, a highly efficient design even by today's standards. However, we can't ignore the superiority of the Gold X-750 Seasonic unit as it bares its teeth at the new Leadex PSU in terms of efficiency, so we think SF could improve the unit's efficiency with a little more fine-tuning.

Efficiency at Low Loads

In the next tests, we measured the efficiency of the Leadex Gold 750 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 more than 500 W capacity). This is important for settings where the PC is in idle mode with Power Saving turned on.

The Gold Leadex unit is pretty efficient with low loads, although it can't compete with its biggest contender, the Seasonic X-750 that easily outperformed it in these tests.

5VSB Efficiency

The ATX spec 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.

All recent SF reviews mention that the 5VSB rail is weaker and less efficient than in other PSUs of the same category. If SF means to catch up to the competition in this area, the 5VSB rail clearly needs to be re-designed to improve its efficiency. That said, its maximum current output has finally been raised from the classical 2.5 A of most PSUs today to 3 A. Not a large increase, it is still better than none at all.

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).

The unit easily meets ErP Lot 6 2013 requirements, but we have seen other Gold units consume close to 0.2 W in standby, and even 0.1 W will make a difference with low loads on the 5VSB rail.

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 36°C-46°C ambient.



A chart that shows the cooling fan's speed (RPMs) and the output noise follows. We measure fan 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 30 dBA during testing, and the results were obtained with the PSU operating in an environment with ambient temperatures between 36°C-46°.



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 ambient temperature were between 28°C and 30°C.



We noticed two ultra-quiet zones in the unit's operating profile, and another two were quiet enough. However, the tide turns as the fan ramps up significantly at 550 W and more, which produces a lot of noise.