Corsair CX650 Power Supply Review

Capable for the mid-range

Corsair CX650 PSU
(Image: © Tom's Hardware)

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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% – 20ms

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Advanced Transient Response at 20% – 10ms

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Advanced Transient Response at 20% – 1ms

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Advanced Transient Response at 50% – 20ms

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Advanced Transient Response at 50% – 10ms

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Advanced Transient Response at 50% – 1ms

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We would like to see a tighter load response at 12V. The voltage drops at 3.3V are quite high as well, leading to below 3.14V in several tests.

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.

There are no notable spikes and voltage overshoots. Good performance overall in this section. 

Power Supply Timing Tests

There are several signals generated by the power supply, which need to be within specified, by the ATX spec, ranges. If they are not, there can be compatibility issues with other system parts, especially mainboards. From year 2020, the PSU's Power-on time (T1) has to be lower than 150ms and the PWR_OK delay (T3) from 100 to 150ms, to be compatible with the Alternative Sleep Mode.

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PSU Timings Table
T1 (Power-on time) & T3 (PWR_OK delay)

The Power-on time is within 100ms, so there won't be any compatibility issues, even with picky mainboards. The PWR_OK delay is out of the 100-150ms region, so the PSU does not support the alternative sleep mode, which will is recommended by the ATX spec.

Ripple Measurements

Ripple represent 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-degree 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).

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10% Load20.5 mV9.2 mV9.7 mV8.7 mVPass
20% Load20.1 mV10.0 mV10.5 mV9.8 mVPass
30% Load21.0 mV10.4 mV11.0 mV10.5 mVPass
40% Load20.5 mV10.8 mV11.0 mV11.8 mVPass
50% Load22.0 mV11.0 mV12.0 mV13.0 mVPass
60% Load25.8 mV11.8 mV13.3 mV14.8 mVPass
70% Load29.0 mV12.9 mV12.9 mV17.5 mVPass
80% Load31.2 mV13.8 mV14.7 mV17.1 mVPass
90% Load34.4 mV14.5 mV15.2 mV19.2 mVPass
100% Load48.6 mV15.8 mV16.6 mV20.3 mVPass
110% Load49.6 mV16.4 mV17.3 mV21.8 mVPass
Crossload 128.4 mV11.9 mV15.4 mV13.1 mVPass
Crossload 248.9 mV15.1 mV15.4 mV20.4 mVPass

Ripple suppression is good for a budget-oriented platform like this one. That said, it would be nice to see below 40mV at 12V, at full load. 

Ripple At Full Load

Ripple At 110% Load

Ripple At Cross-Load 1

Ripple At Cross-Load 2

EMC Pre-Compliance Testing – Average & Quasi-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 nearby devices.

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

(Image credit: Tom's Hardware)

Comments on EMC.

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Contributing Editor

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

  • mdd1963
    Lots of folks 'poo-poo' some of Corsair's PSU offerings, instead flocking to something w/Gold or Platinum in it'/s title, no matter the 150% price increase, and/or the 430W 'only' capacity...

    I've been happily using a Corsair 600 watt PSU (CX600) which cost me all of $55 or so in Feb 2017 if I recall correctly... ; never a stutter.
  • grmaster
    any specific reason why this platform is so bad at advance transient response at 12v