Skip to main content

Fractal Design ION+ 660P Power Supply Review: Compact And Silent

Transient Response Tests, Ripple Measurements and EMC Pre-Compliance Testing

Advanced Transient Response Tests

For details about our transient response testing, please click here.

In the real world, power supplies are always working with loads that change. It's of immense importance, then, for the PSU to keep its rails within the ATX specification's defined ranges. The smaller the deviations, the more stable your PC will be with less stress applied to its components. 

We should note that the ATX spec requires capacitive loading during the transient rests, but in our methodology, we also choose to apply a worst case scenario with no additional capacitance on the rails. 

Advanced Transient Response at 20% – 200ms


Advanced Transient Response at 20% – 20ms


Advanced Transient Response at 20% – 1ms


Advanced Transient Response at 50% – 200ms


Advanced Transient Response at 50% – 20ms


Advanced Transient Response at 50% – 1ms

Image 1 of 8

Image 2 of 8

Image 3 of 8

Image 4 of 8

Image 5 of 8

Image 6 of 8

Image 7 of 8

Image 8 of 8

The transient response is satisfactory on all rails, especially the minor ones.

Turn-On Transient Tests

In the next set of tests, we measure the PSU's response in simpler transient load scenarios—during its power-on phase. Ideally, we don't want to see any voltage overshoots or spikes since those put a lot of stress on the DC-DC converters of installed components.

Image 1 of 3

Image 2 of 3

Image 3 of 3

The results of these tests are very good.

Ripple Measurements

Ripple represents the AC fluctuations (periodic) and noise (random) found in the PSU's DC rails. This phenomenon significantly decreases the capacitors' lifespan because it causes them to run hotter. A 10 degrees Celsius increase can cut into a cap's useful life by 50%. Ripple also plays an important role in overall system stability, especially when overclocking is involved.

The ripple limits, according to the ATX specification, are 120mV (+12V) and 50mV (5V, 3.3V, and 5VSB).

10% Load12.7 mV3.9 mV10.9 mV6.8 mVPass
20% Load8.0 mV4.1 mV10.7 mV6.9 mVPass
30% Load7.9 mV6.0 mV14.7 mV10.0 mVPass
40% Load8.3 mV5.3 mV11.8 mV7.7 mVPass
50% Load8.5 mV5.7 mV11.7 mV7.7 mVPass
60% Load8.8 mV6.7 mV13.1 mV8.7 mVPass
70% Load9.4 mV6.2 mV13.2 mV8.7 mVPass
80% Load10.2 mV7.1 mV15.2 mV9.4 mVPass
90% Load10.8 mV7.4 mV14.8 mV10.2 mVPass
100% Load16.3 mV8.7 mV15.5 mV11.0 mVPass
110% Load17.8 mV8.9 mV15.3 mV10.8 mVPass
Crossload 111.0 mV5.2 mV16.0 mV7.4 mVPass
Crossload 216.2 mV7.5 mV12.4 mV10.0 mVPass
Image 1 of 4

Image 2 of 4

Image 3 of 4

Image 4 of 4

Ripple suppression is very good on all rails.

Ripple At Full Load

Image 1 of 4

Image 2 of 4

Image 3 of 4

Image 4 of 4

Ripple At 110% Load

Image 1 of 4

Image 2 of 4

Image 3 of 4

Image 4 of 4

Ripple At Cross-Load 1

Image 1 of 4

Image 2 of 4

Image 3 of 4

Image 4 of 4

Ripple At Cross-Load 2

Image 1 of 4

Image 2 of 4

Image 3 of 4

Image 4 of 4

EMC Pre-Compliance Testing – Average and Peak EMI Detector Results

Electromagnetic Compatibility (EMC) is the ability of a device to operate properly in its environment without disrupting the proper operation of other close-by devices.

Electromagnetic Interference (EMI) stands for the electromagnetic energy a device emits, and it can cause problems in other close-by devices if too high. For example, it can be the cause of increased static noise in your headphones or/and speakers.

The conducted EMI emissions are in control.

MORE: Best Power Supplies

MORE: How We Test Power Supplies

MORE: All Power Supply Content

Aris Mpitziopoulos
Aris Mpitziopoulos is a Contributing Editor at Tom's Hardware US, covering PSUs.