Temperature and Noise
Each Corsair PSU, like its Seasonic counterpart, is cooled by a 7-blade 120mm Sanyo Denki San Ace 120 fan (model number: 9S1212F404, rated speed: 2200 RPM). Such fans are high-quality products with individual balance correction and do not produce any unwanted sounds at work. All you can hear is the pure aerodynamic noise, irrespective of the fan’s speed.
About one fourth of the impeller is covered with a piece of transparent plastic to optimize air flows inside the PSU.
Notwithstanding the identical fans, the PSUs differ in noisiness because they differ in wattage. The speed regulation algorithm has remained the same since the Seasonic X Gold, though. The fan is mostly idle until a load of 150 watts (it may turn on and work for a while at below 400 RPM). Then, it rotates at a constant and low speed (less than 600 RPM) at loads up to 400 watts. And then it accelerates in a linear manner. The acceleration is so fast that the temperature of the PSU components lowers rather than stays at the same level.
The medium model is a perfect illustration of Seasonic’s fan regulation algorithm. The other two models have their peculiarities, though.
The highest-wattage model had its fan running at 1950 RPM by the 775-watt mark. Then the fan stopped to accelerate and the difference in temperature between the incoming and outgoing air began to increase again.
The junior model doesn’t have a long stretch of constant speed or a sudden acceleration at high loads. As a result, its fan speed at a load of 650 watts is the lowest among all the PSUs based on this platform we've tested so far: 1400 RPM instead of the usual 1500-1600 RPM.
Efficiency and Power Factor
Every PSU has a power factor of 0.98 to 0.99. That’s a high result.
The PSUs had the following efficiency at the reference loads of 20%, 50% and 100%:
- AX650: 88.8%, 92.2%, 90.2%, with peak efficiency of 92.7% at 290 W;
- AX750: 88.4%, 91.3%, 89.5%, with peak efficiency of 92,7% at 301 W;
- AX850: 88.6%, 92.1%, 87.9%, with peak efficiency of 92.1% at 50% load.
Thus, every PSU proved its compliance with the 80 PLUS Gold certification (87%, 90% and 87%).