Corsair CX750M (2021) Power Supply Review

The Corsair CX750M offers much for its price.

Corsair CX750M (2021)
(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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Transient response is good at 12V, decent at 5V and mediocre at 3.3V. 

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 is a notable step at 5VSB, and the 12V slopes are not so smooth. Nonetheless, these results won't create any issues.

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 PWR_OK delay is within the 100-150ms region, so the PSU supports the alternative sleep mode recommended by the ATX spec.

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-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% Load8.3 mV8.5 mV12.9 mV10.9 mVPass
20% Load9.4 mV8.4 mV15.2 mV11.2 mVPass
30% Load10.4 mV9.6 mV16.7 mV11.7 mVPass
40% Load11.9 mV11.0 mV17.7 mV13.6 mVPass
50% Load12.1 mV11.6 mV18.7 mV13.9 mVPass
60% Load14.7 mV12.2 mV20.2 mV15.9 mVPass
70% Load19.3 mV11.6 mV22.4 mV18.7 mVPass
80% Load24.3 mV12.3 mV24.8 mV33.3 mVPass
90% Load29.4 mV13.6 mV25.9 mV39.4 mVPass
100% Load38.3 mV18.0 mV30.8 mV23.5 mVPass
110% Load45.8 mV20.9 mV31.7 mV25.3 mVPass
Crossload 123.4 mV13.0 mV22.8 mV40.5 mVPass
Crossload 211.0 mV11.3 mV10.7 mV24.8 mVPass
Crossload 316.9 mV10.0 mV21.8 mV32.4 mVPass
Crossload 439.2 mV15.6 mV21.1 mV14.0 mVPass

Ripple suppression is decent. It would be nice, though, to see the same ripple levels with the previous CM750M unit. 

Ripple At Full Load

Ripple At 110% Load

Ripple At Cross-Load 1

Ripple At Cross-Load 4

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 cause increased static noise in your headphones or/and speakers.

΅We use TekBox's EMCview to conduct our EMC pre-compliance testing.

(Image credit: Tom's Hardware)

EMI emissions are low. The corresponding filter does a splendid job!

MORE: Best Power Supplies

MORE: How We Test Power Supplies

MORE: All Power Supply Content

Aris Mpitziopoulos
Contributing Editor

Aris Mpitziopoulos is a contributing editor at Tom's Hardware, covering PSUs.

  • Co BIY
    Another great review!

    Why do you prefer a full modular cable set up to this semi-modular ? At this price point I think semi-modular is "best". One less failure point and greater efficiency. I don't think custom cabling is a consideration for this range. I think Semi-modular should be considered best practice outside of Vanity/RGB/Bling focused lines.

    For appearance sake I do think the exit point of a semi-modular "main cable" of could be made to visually match the other cables without giving up the advantages.