NZXT C Series 750W Power Supply Review

The NZXT C750 is an 80 Plus Gold certified power supply with ETA-A and LAMBDA-S efficiency and noise certifications, from Cybenetics. While it isn't among the quietest 750W power supplies, with up to 450W loads, it won't bother users who are sensitive to noise. Nonetheless, the Corsair RM750x and RM750, the Asus ROG Strix 750, and the XPG Core Reactor 750 are more suitable choices for users that set low noise output as priority one. The overall performance is about the same as the Seasonic Focus Plus Gold 750, so it is pretty high. But this is a tough category, so the C750 cannot claim a top place in our best power supplies.

 NZXT's C750 is the middle of the C series lineup. We have already evaluated the C850 and the C650, so we had to take a look at the C750 since the 750W category is highly popular among users, because it offers enough power to build a potent gaming system equipped with 8-core Intel or 12-core AMD processors and Nvidia RTX2070/2080 or AMD 5700XT graphics cards. If you plan on using more than one high-end graphics cards, then you should look for a stronger power supply with 1000W capacity, at least, just to be sure that you won't have any power issues. 

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Product Photos

Like its siblings, the C750 uses the same platform as the Seasonic Focus Plus Gold, so we expect good and reliable performance along with high-enough efficiency levels. This platform isn't modified, though, to allow for higher than 70% efficiency at super-light loads (2% of the PSU's max rated capacity), and it doesn't support the alternative sleep mode, which allows the system to instantly wake-up from sleep. The latter doesn't look so remarkable from the moment there are no available mainboards on the market to support the feature. Still, when you buy a new power supply, you should think long-term, because the PSU is a component you could use across several builds.

All C series models feature a fully modular cable design and have compact dimensions, thanks to 150 mm depth. The cooling fans use fluid dynamic bearings and are supported by a semi-passive operation, which turns off the fan under light loads. Users have the option to deactivate this and allow the fan to spin throughout the entire load range.

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Product Photos

Specifications

Power Specifications

Cables & Connectors

Our sample came with only one EPS connector, but according to NZXT's PR, all C650 and C750 will be equipped from now on with a second EPS cable, raising the number of corresponding connectors to two. Thanks to the vast increase of cores in modern CPUs, a pair of EPS connectors is required in all high-end mainboards. 

Each of the two cables host a pair of PCIe connectors. The length of the PCIe cables is notable. Usually, these cables are shorter than the EPS one(s).  Finally, there are plenty of peripheral connectors, but the distance between them is too short at 100 mm.  Lastly, the inclusion of inline caps in the ATX, EPS, and PCIe cables can be a problem during cable management. 

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Cable Photos

Component Analysis

We strongly encourage you to have a look at our PSUs 101 article, which provides valuable information about PSUs and their operation, allowing you to better understand the components we're about to discuss.

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Overall Photos

We have seen this platform numerous times so far. Besides the highly popular Focus models, Seasonic also provides this platform to several large brands. The design is up to date, and for increased efficiency and high power handling, Seasonic uses a full-bridge topology on the primary side, which is supported by an LLC resonant converter. On the secondary side, we meet the usual stuff: synchronous rectification where FETs regulate the 12V rail and a pair of VRMs for generating the minor rails. To keep the cost down, Seasonic used Great Power FETs as primary switchers instead of more expensive Infineons. Nonetheless, less stress is applied to the main FETs because of the full-bridge topology. No expense was spared in the other parts of this power supply, with the only exception the Chemi-Con KZE caps, which are not as good as the KY ones. 

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Transient filter

The transient filter is complete. Still, its performance is not among the best we have seen. 

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Bridge rectifiers

The pair of bridge rectifiers can handle up to 30A of current, combined. 

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APFC converter

The APFC converter uses two Infineon FETs and a single boost diode, provided by STMicroelectronics, which is strong enough to handle this PSU's needs. The bulk cap is provided by Chemi-Con and has enough capacity to allow for a much longer than 17ms, hold-up time.  

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Main FETs and primary transformer

Four switching FETs are installed in a full-bridge topology. Although this topology is considered an expensive option, you can save money since the FETs take less stress, so that you can use lower quality ones compared to a similar spec half-bridge topology. We recently saw this in our DeepCool GamerStorm DQ-M V2L 850W review. 

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12V FETs and VRMs

Four Nexperia FETs handle the 12V rail, while a pair of DC-DC converters generate the minor rails. These converters use six Infineon FETs, and the common PWM controller is provided by Anpec. 

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Filtering caps

The Chemi-Con KZE caps don't have such a high life but are usually met in good power supplies, and if they are combined with other, higher quality caps, they don't bring any trouble in the long run. Besides the KZE caps, we also find W, KY, and two Rubycons (YXG). Many polymer caps are also used for ripple filtering purposes. 

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5VSB Circuit

The 5VSB circuit's PWM controller is an Excelliance MOS EM8569. On the secondary side of this circuit, a Schottky Barrier Diode (SBR) is used, so inevitably efficiency will take a hit. 

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Modular board front

Several polymer caps are installed at the front side of the modular board. There are empty spots for several more, as you can see in the photos above. 

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Soldering quality

As usual, we don't have any complaints from Seasonic's manufacturing quality. 

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Cooling fan

Hong Hua dominates the PSU fan market nowadays since it manages to deliver good quality and performance at affordable prices. It is nice to see FDB fans everywhere instead of low-quality sleeve bearing fans. 

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