NZXT C750 Review: Which Power Supply to Choose for Your Workstation?

If you are building a high-performance workstation, regardless of whether you will use the calculations on a CPU or GPU, the power supply is the node that is traditionally chosen on the basis of the principle "the more expensive the better." As a rule, users prefer to take a model with a power reserve, overpaying for 1-Kilowatt options, which is completely optional.

The fact is that even a modern workstation for mathematical problems, working with video or scientific projects usually consumes 400-500 watts. If your computer uses calculations mainly on the CPU, then a system with a top-end AMD Threadripper/EPYC or Core i7/i9 will require about 350 W, as they say, "from the socket." In machines with three GPUs, the typical consumption can be around 600W, depending on the graphics card model. The optimal power supply for such configurations will be 600-900 W, and it hardly makes sense to overpay for more.

The state of affairs in the modern power supply market

In today's globalized world, brands such as NZXT, CoolerMaster or Thermaltake no longer manufacture or develop power supplies: they use the production facilities of Seasonic, FSP or Delta, and no one will tell you in advance which platform this or a different line of power supplies. The only option for choosing a power supply in terms of quality is the "80 Plus" type of certificate assigned to this power supply. Cheap Chinese do not even get a silver medal, and in order to somehow sell them, a new “80 Plus” certificate was introduced especially for them without the prefix “Silver”, “Gold” or “Platinum”.

Usually, a power supply with a "just 80 Plus" certificate is a fierce Chinese thing, which, when plugged into an outlet, clicks inside, over time begins to make noise, but it can fail at any time. The anti-record of our testlab is 2 weeks, after which all of a gaming PSU with sparks and smoke went to the land of eternal hunting with gratitude that he did not have time to grab the motherboard.

I believe that during its existence, the 80 Plus certificate has dropped exactly one notch. If we compare the quality and brand of components, then today's Gold is equal to Silver from ten years ago, Silver is disappearing from sale, Bronze is already fierce Chinese, so if you really want to take a thing, then choose a model with 80 Plus Gold, Platinum or Titanium. And do not think that the situation is different in Lenovo/HPE/Dell branded workstations: globalization has put everything in its place, and if there is no 80 Plus Gold certificate, then in such computers there will be the same Chinese as in power supplies. purchased in the online store.

All other distinctive features come down to the choice of who has more oily oil, or who has some useful trick, such as software monitoring, RGB lighting or fan noise control. And the last - this is the most basic parameter that you will feel when working on your new machine every day, because whatever one may say, and if a powerful computer is also silent - this is bingo!

NZXT C750 construction

The NZXT C750 we are reviewing is built on the Seasonic Focus Plus Gold platform, which has the ability to turn off the fan at low load, so that the power supply is absolutely silent. This mode is turned on in the most reliable way: with a button on the wall outside the PSU, and most importantly, when the load rises to 350 W, the fan starts up so as not to cause overheating of the components, and when the load decreases again, the power supply goes into silent mode again.

Keep in mind that to activate this "hybrid" mode, the button on the back must be depressed!

In general, the choice of fan looks strange: it uses a 120-mm model HA1225H12F-Z from Hong Hua with a blade speed of 2000 RPM, a hydrodynamic bearing with a service life of 50,000 hours is used in the rotor suspension. The angle of attack of the blades is designed primarily to create high pressure, which is typical for all fans of power supplies. There is no speed regulation, so the cooling system only works in ON/OFF modes.

I was asked in the review to show that all capacitors in the NZXT power supply are Japanese-made, from Nippon Chemi-Con KZE series. They are, of course, for the most part electrolytic, not solid-state, but these are the highest quality cans that can be found in consumer electronics today. They have a temperature coefficient of 2000 hours at 105 degrees Celsius, which is approximately 12 years of normal operation. I think that the manufacturer specifically chose Nippon electrolytes, because they are well recognizable by their brown color and do not need any introduction. Solid-state containers are also used here: the blue ones are from the same Nippon, but the manufacturer of the red ones could not be recognized (if it is Sanyo, then fine, but let's not speculate).

A full-fledged filter is wired at the input, in which two chokes are located on the main board, and capacitors are located on the input board. A varistor is also installed here, which protects the power supply from increased input voltage. You've probably heard about the presence of OVP (Over Voltage Protection) in power supplies, but few people wondered how it works. So, when the voltage at the input rises, the varistor connected between phase and zero lowers its resistance, causing a short circuit at the input, which triggers the machine at the entrance to the office or, in simple terms, knocks out plugs. Thus, one such power supply with overvoltage protection protects all equipment plugged into an outlet on the same branch as your computer. In general, a varistor is a cheap option, which, from my point of view, should be in all power supplies, but unfortunately the Chinese often save on this.

Two diode bridges are located on a common radiator. DC-DC converters +5 and +3.3 V are located on the daughter board and share a common aluminum heatsink. If you look closely, even on the ferrite rings around which the filters are wound, there is a manufacturer's mark, which is now a rarity.

The NZXT C750 PSU is fully modular, meaning you can unplug all cables including the ATX24 Pin. Why this may be needed is completely understandable: for the convenience of connection in some unusual cases. The connectors for connecting cables are located on a separate daughter board and have 7 capacitive filters: 3 electrolytic and 4 solid-state capacitors, produced by the same Japanese Nippon.

Of course, Seasonic, which manufactures power supplies for NZXT, is a recognized leader in quality in its business, and happily sells its power supplies under its own brand, but there are still differences between OEM and NZXT: the latter is assembled on black boards and has a more accurate soldering than the original. There are no traces of unwashed flux, and there is absolutely nothing to complain about in the design here: the power supply unit is assembled inside so that at least put it on display!

Testing

First of all, let's check the voltage drop across the buses at different loads.

Line voltages under load

Deviations within normal limits.

Efficiency, %

The power supply unit shows the greatest efficiency in the range of 400-600 W, the noise level is 36 dB, and given that the power supply unit looks at the floor with a fan, even its operation does not cause inconvenience.

Specifications

Pay attention to the warranty period - 10 years! In today's world of disposables, this is just some kind of madness that I fucking love!

Package Contents

As expected, the NZXT C750 is packed royally: in a separate case there is the power supply unit itself, and next to it there are cables in the purse so that you can store all unnecessary cables in one place.

The cables themselves do not represent anything special either by the thickness of the cores, or by the insulation, or by the connectors.

Conclusions

In a good workstation, the cost of a power supply unit will be negligible compared to the cost of a processor, memory, GPU and SSD. Therefore, you should only choose high-quality models that use branded components, and have technologies that you can experience on your own skin. Modern GPUs have already learned how to turn off fans in idle mode, so building a silent workstation is far from fantasy, and a power supply that can work with zero noise is a great addition to the overall concept.

NZXT C750 is, first of all, the high quality of the Seasonic platform, which in this particular case has become even higher (another PCB, more accurate installation), and the only thing that can be found fault with is the model of the fan used. But again, there are no massive complaints about it.

The power supply has high efficiency and voltage quality indicators, and a crazy 10-year warranty speaks of quality better than a thousand other reasons.

Mikhail Degtyarev (aka LIKE OFF)
19/05.2020