Articles: Cases/PSU

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Output Voltage Ripple

The high-frequency voltage ripple is higher than with the X Gold series but far below the requirements of the industry standard.

The same goes for the low-frequency ripple at the double mains frequency.

Temperature and Noise

Large fans have become conventional in PSUs, but the SS-1000XP Active PFC F3 can do with a modest 120mm fan thanks to its high efficiency. There should be no problems in terms of cooling and noisiness if the fan regulation algorithm is right (the high-efficiency FSP Aurum series is a bad example of such an algorithm).

The PSU is cooled by a Sanyo Denki fan (San Ace 120, 9S1212F404) that is also employed in other products from Seasonic and Corsair. Seasonic claims that this model boasts a number of exclusive advantages: triple balancing of the copper axis, specially shaped blades that ensure high efficiency at minimum noise, long-lasting design with ball bearings. As a matter of fact, in our earlier reviews we noticed Sanyo Denki fans to have been individually balanced, which contributes to their low noise and long service life.

This fan is blameless, too. However, its honeycomb-mesh grid would produce some unwanted aerodynamic sounds when the speed of the fan was as high as 1000 RPM. On the other hand, this means very high loads at which there will probably be much more prominent sources of noise in the computer system.

The PSU’s fan can work in two modes: Normal (selected by default) and Hybrid.

You can change the mode by means of a switch near the connectors (when you install the PSU into a system case, that switch will be inside the chassis).

The default Normal mode means a standard regulation algorithm with the fan rotating at a low speed until a certain load/temperature. After that threshold, its speed begins to increase in a linear manner.

The low-load speed of the fan is about 650 RPM. It is only at a load of 700 watts that the fan accelerates and it does so proactively, reducing the temperature rather than just keeping it at the same level.

The Hybrid mode is going to be demanded by users who don’t often run heavy applications but value silence. The fan does not work at all when the load and temperature are low. As the load grows higher, the fan starts up at a very low speed (below 500 RPM) and then accelerates some more.

According to its specs, the PSU is cooled passively until a temperature of 25°C and loads of 30%, but in my test the fan would start up intermittently only at loads above 350 watts. The fan was rotating constantly at loads of 400 watts and higher. The ambient temperature was 23°C and the internal temperature of the PSU was surely higher than the specified 25°C for passive mode: the difference between the incoming and outgoing air was as large as 15°C.

The fan accelerates in a linear way at high loads and, just like in the Normal mode, the temperature goes down rather than stays at the same level.

This ensures better thermal conditions for PSU components, but the PSU might have been even quieter at high loads if its fan wasn’t so aggressive. Well, even with this regulation algorithm the fan is only 1000 RPM fast at a load of 800 watts. Its noise only becomes audible at loads of 900 watts and higher.

So, the two modes are roughly equal when it comes to high loads, but the Hybrid mode is quieter at low and medium loads (the fan doesn’t work at all at loads up to 350 watts and its speed is lower than in the Normal mode at loads up to 600 watts). On the other hand, the fan is very quiet at the speed of 650 RPM that it has at low loads in the Normal mode, so both modes are very comfortable.

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