NZXT C Series 650W Power Supply Review

A quiet power supply with a fair price.

(Image: © NZXT)

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Protection Features

Check out our PSUs 101 article to learn more about PSU protection features.

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Protection Features



12V: 75.38A (139.59%), 12.006V
5V: 27.2A (136%), 5.027V
3.3V: 27.6A (138%), 3.317V
5VSB: 6.1A (203.33%), 4.98V


918.42W (141.3%)


✔ (181°C @ 12V Heat Sink)


12V: ✔
5V: ✔
3.3V: ✔
5VSB: ✔
-12V: ✔


Proper Operation



Surge: MOV
Inrush: NTC Thermistor & Bypass Relay

The OCP triggering points are set high on all rails, and the same goes for OPP. We can understand why NZXT needs lots of headroom at 12V to cope with the high power spikes that some graphics cards can create, but there is no reason for such high OCP points on the minor rails. The 5V and 3.3V rails are lightly used in modern systems. Finally, the PSU might be able to deliver close to 920W without any problems under normal operating temperatures. Still, it will be highly stressed with such a high power output under increased temperatures. This is why we suggest OCP and OPP triggering points within the 130% range, given that the platform can handle it, of course. 

DC Power Sequencing

According to Intel’s most recent Power Supply Design Guide (revision 1.4), the +12V and 5V outputs must be equal to or greater than the 3.3V rail at all times. 

Unfortunately, Intel doesn't mention why it is so important to always keep the 3.3V rail's voltage lower than the levels of the other two outputs.

The 3.3V rail is lower than the other two in all tests we conducted, so there everything is fine here. 

Cross Load Tests

To generate the following charts, we set our loaders to auto mode through custom-made software before trying more than 25,000 possible load combinations with the +12V, 5V, and 3.3V rails. The deviations in each of the charts below are calculated by taking the nominal values of the rails (12V, 5V, and 3.3V) as point zero. The ambient temperature during testing was between 30 to 32 degrees Celsius (86 to 89.6 degrees Fahrenheit).

Load Regulation Charts

Efficiency Chart

(Image credit: Tom's Hardware)

Ripple Charts

The lower the power supply's ripple, the more stable the system will be and less stress will also be applied to its components.

Infrared Images

We apply a half-load for 10 minutes with the PSU's top cover and cooling fan removed before taking photos with a modified FLIR E4 camera able to deliver an IR resolution of 320x240 (76,800 pixels).

The temperatures are kept at low enough levels,  so we wouldn't expect reliability issues with the relaxed fan profile. 

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Aris Mpitziopoulos
Contributing Editor

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