Corsair CX750 750W Power Supply Review

The Corsair CX750 is, "An ideal choice for value-conscious system builders and upgraders." So when saving a few bucks and buying a Corsair Bronze rated power supply do you still get a PSU that can deliver clean power under load? We are hoping that fewer bells and whistles does not equate to less quality in the wattage department.



Over the years, we have seen a number of 750W power supplies from Corsair but the Corsair CX750 is the first member of Corsair’s CX lineup of power supplies that we have seen. Over the years, those 750W models have generally been good except for one notable exception in the RM750. Today though, we are seeing a 750W product that Corsair is targeting at a bit more of an entry level than we have seen from Corsair in years and the last entry level-ish power supply we saw from Corsair (the CS550M) was not good. So, the question becomes; will the CX750 follow in the wake of the previous good 750W units we have seen or will it follow in the wake of the more recent RM750 and the CS550M?

HardOCP’s testing methodology is intended to very much push power supplies to their advertised wattage rating in temperatures that will represent some of the hottest computer enthusiast cases. So if a unit passes all our testing it is definitely not something to take lightly. In fact we expect more power supplies to fail our testing than make it through unscathed.

Build Quality

The Corsair CX750 is an entry level product according to Corsair and, if you adjust your expectation to that of a generic entry level product, you probably won't be disappointed with the build quality but that doesn't mean it is as good as it should or could be at this price point. Now, that said, the build quality of the exterior of the unit is generally good, if formulaic, and similar to what we saw with the CS550M. It does have a rather large QC issue with the cabling as it was extremely poorly done and this was still shipped out to retail in this shape rather than having someone take the few seconds necessary to fix the issue. When we flip to the interior, the build quality of the Corsair CX750 is generally good but suffers from some bad design choices and some lower quality components. A couple of the high points first though are the integration which featured excellent soldering, the Nippon Chemi-con capacitors, the Enesol solid capacitors, and the rather modern topology. OK, so the low points come from the CapXon capacitors, the lack of heatsinking on the 12v power components, and the decision to stick the DC-DC VRMs on a PCB attached to the side of the housing for no apparent reason other than to starve these components of airflow. Backing up all of this is a woefully short 3 year warranty which should make no one except Corsair jump for joy when you see it paired with those design choices above. Lastly, the documentation from Corsair continues to be wretched and that would be an easy fix if someone was so inclined, clearly Corsair is not though.

Load Testing

Is that an iceberg on the horizon? Yes, yes it is, and the Corsair CX750 sails right into and then goes straight to a watery grave. Starting things off today, we have the voltage regulation when this unit was functional. In our testing, the 12v rail showed a peak change of 0.16v while the 5v had a peak change of 0.06v and the 3.3v rail had a peak change of 0.05v through Test #3. Now, since this unit failed Test #4 and the Torture Test for reasons other than a poorly designed fan controller, this unit manages to be the worst performing 750W power supply we have seen from Corsair and that includes the RM750! Now, when we look to the competition things get a bit harder as we have not seen a lot of "feature comparable units" recently but we have seen a couple comparably priced units that this will be competing against as most people tend to look at similarly priced products when buying things. The news is not good on that front as this unit is bested by all of these products including the Rosewill Captone 750W, the Antec TP-750C, and even the FSP Raider 750W which also failed our testing. Indeed, this unit could not even keep pace with the failed Raider 750W as that unit could make it into Test #4. Now, when we look over at the efficiency numbers, we see that this unit ranged from 84.10% to 86.17% efficient at 120v and 82.98% to 84.84% efficient at 100v. When we look at the 80 Plus results we see that using 80 Plus’s loads, and conditions, the CX750 was 82.27%-86.39%-81.95% efficient. While decent, values like that mean that this unit falls short of the 80 Plus Bronze category by 0.05% at full load. That, however, is just about a rounding error so we can't fault this unit too much on that point. We can, however, fault it for also failing the 80% load Torture Test after just a few minutes time.

Moving on to the Transient Load Tests, we see that this unit posts values that are passing but I wouldn't take too much from that one fleeting moment of adequacy. During our Transient Load tests, the 12v rail had a peak change of ~360mV and the loaded 5v rail had a peak change of ~190mV while the unloaded 5v rail during the 12v load had a peak change of ~60mV. Those numbers are all fairly simple and straightforward but the reason I would not take too much from that is that this unit was just tied with the FSP Raider 750W and the Rosewill Capstone 750W while trailing the Antec TP-750C. So, the high point of testing today is tied for average. Not great, but at least passing.

DC Output Quality

When we turn our attention to the DC output quality of the Corsair CX750, we again see this unit was a failure. For the tests it did complete, the CX750 does well actually as the peak trace amplitudes were ~25mV on the 12v rail, ~15mV on the 5v rail, and ~10mV on the 3.3v rail. Values like that were actually inline with what we saw from the Rosewill Capstone 750W and ahead of the FSP Raider 750W as well as the Antec TP-750C. However, and most importantly, that was just for 3/5 of testing as all of those units made it further and only the Raider 750W failing. On top of that, the Raider 750W failed later in testing than the CX750 so even that is an uneven comparison. So, we can't say for certain how this unit would have done relative to other units but we can say that if this unit is running, and that is not a qualifier you like to use, it seems to do OK. If you push the unit a little to full power, or even 80%, then who knows how this unit will do.


Corsair bills the CX750, like just about all of its products, as being a quiet power supply. With this in mind we see that it does have a large overhead sleeve bearing fan and it comes in at less than absurd power levels. However, it is somewhat hampered by that fan not being the best quality and efficiency that, today, is not great. That said, the fan controller on this unit could still make it quiet if it was well designed. As we already know though, our evaluation is not complete as this unit failed load testing. However, when it was running the CX750 was noticeable by the end of Test #3 and then become much more so as it tried to perform in the Torture Test and Test #4. With that as a frame of reference, I would not call this unit quiet overall even though it certainly would be under a situation like Test #1. This doesn't seem like it should be much of an issue though as users who are looking to buy the cheapest thing with a Corsair name on it aren't going to be the target audience for a quiet cooling solution; otherwise they would be looking to pay more or they would be buying another brand. If for some reason someone is under the impression that scraping the bottom of the barrel is going to get you real value added features like a high quality fan then; no, not with this unit but it has bigger issues than that already.

Paul's Thoughts:

I think we have done a rather good job of documenting the kind of slow spiral downward that Corsair power supply products have taken over the last 5 years. That 5 year time frame is not a joke either. In writing this review, I went back and read my notes, the reviews, and my "Paul's Thought's" section for each Corsair power supply review from the last 5 years and the last product that Corsair produced that was a real "WOW" product was the AX850. It was then the TXv2 products that started the "OK it's a replacement unit but still good" trend that then lead to the precipitous drop after that to "meh" or worse. Now, we buy a number of power supplies that you see reviewed here either as the review unit or to verify product we are provided and, in the last few years, every time I have gone to buy products I see the flood of Corsair units that everyone does. However, I have avoided Corsair units since the ones we have been working with have just been kind of "meh" or worse and these just don't make the greatest review material when the answer is "meh, you should buy something else" rather than "this is AMAZING!" The Corsair CX750 reviewed here today comes from a stack of power supplies that HardOCP purchased in retail over the Black Friday / Cyber Monday shopping period.

Among the deals that hammered my inbox from Newegg, Microcenter, Amazon, Best Buy, Tigerdirect, etc the vast majority of power supplies were Corsair units of various types and the CX series showed up with impressive frequency. So, if this is the product line being pushed when everyone was shopping for gifts over Black Friday we might as well see what your Black Friday bargain hunting got you.

Unfortunately, what it got us was buyers remorse unlike the Rosewill Capstone 750W we bought for the same price. Who would have thought in 2009, or 2010, or 2011 that today we would be sitting here saying, "Skip the Corsair, buy the Rosewill since it is literally better at everything than the Corsair product at the same price point." For those who are going to point out that we are looking at sale pricing you are correct, but at the time of purchase the regular list price made the Capstone 750W less expensive and at the time of writing the Capstone 750W is the same price as the CX750 and that makes it worse. Looking back now, the real bottom end of the spectrum was the last part of the current Corsair power supply portfolio that we had not seen recently(ish) and after seeing it today, there is nothing here for users to be interested in. This somewhat reminds me of the OCZ/PC Power & Cooling story. Hopefully, Corsair will right the ship to avoid the same fate as OCZ/PC Power & Cooling.

The Bottom Line

The Corsair CX750 is an entry level product from Corsair and, today, it performs a good bit below even those standards given that Corsair used to produce quality products from top to bottom. This unit’s current product placement is readily apparent from the outset as the build quality has issues, particularly noticeable since these are coming from a "name brand" and not a "no name" company. The 3 year warranty support is probably trying to tell us something as well. The unit is not very quiet, and the performance just falls flat as it can not complete testing.

Sure, someone will point out that this is an entry level product and we are reviewing it like it was a "quality" product. Fair enough, but we did the same thing recently to the Rosewill Capstone 750W and that unit thrived, so entry level priced units can indeed be quality units and that is truly what users want. On top of that, for the current $89.99 you pay for this unit you can get that Rosewill Capstone 750W with money to spare, you can get the FSP Raider 750W (not a good choice but it is a better choice than this), and you can get Antec TP-750C today for $54.99 after $30 MIR.

The bottom line is simply this; there is absolutely no reason ANY user should buy a Corsair CX750 as you can get better performing, better built, and better supported products for about the same price or even for much less money. That is unfortunate since Corsair has such a dominate position in etail and retail and users are snapping up lots of these kinds of products based on the name brand only to end up with a product less capable than other options.

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Corsair CX750 آ— 80 PLUSآ® Bronze Certified Power Supply