Corsair AX1500i Titanium PSU Review

Today, we're taking a look at Corsair's flagship power supply unit. The AX1500i is a digital, 1500 watt, 80 PLUS Titanium-rated beast of a PSU!

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Tom's Hardware Verdict

Our final verdict can be summarized as follows: this is best PSU that money can buy today.

Pros

  • +

    Full power at 49°C

  • +

    Powerful

  • +

    Highly Efficient

  • +

    Ripple Suppression

  • +

    Load regulation

  • +

    Silent Operation

  • +

    Digital control and monitor

  • +

    Amount of connectors

  • +

    Fully modular

  • +

    Long cables

  • +

    Japanese electrolytic caps

  • +

    Hold-up time

  • +

    Warranty

Cons

  • -

    Large dimensions

  • -

    Small distance between Peripheral connectors

  • -

    Accuracy of Corsair Link's readings

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Corsair AX1500i Power Supply Review

Corsair's flagship power supply unit (PSU) offering, the AX1500i, is the best PSU money can buy today, according to many experts in the field. The AX1500i stands out not only because of its extremely high performance but also its rich features and digital platform. Currently, the AXi series is Corsair's top PSU line, consisting of four digitally controlled units with capacities ranging from 760W to 1500W. The introduction of this line was made with the AX1200i model, which easily conquered the top place in its category; afterward, Corsair released the two lower-capacity AXi models. In 2014, Corsair took a huge step forward with the introduction of the AX1500i, which features significant improvements compared to the other AXi PSUs. The AX1500i is the only PSU in this line that meets the 80 Plus Titanium efficiency requirements, which is a massive accomplishment, considering the huge capacity of the unit.

So far, we have seen several digital PSUs from various manufacturers, including CWT, Enermax and Etasis. However, none of them offers a fully digital power supply, meaning that, in most cases, only a few circuits are digitally controlled and analog controllers are used for the rest. For most manufacturers, the main reason for not going fully digital is related to increased production costs. But for digital circuits, you also need an experienced engineering team to leave analog designs behind. Currently, the AX1500i and the AX1200i units feature an almost fully digital platform, as all rails except for the 5VSB rail — along with the APFC converter, the primary side and the protections of the PSU — are controlled by processors, not by analog controllers. If the 5VSB circuit featured digital control as well, then the platform could be considered a purely digital platform. In terms of optimal performance, the 5VSB rail isn't important enough to justify the increased costs of a digital circuit.

Specifications

In addition to offering Titanium efficiency, the AX1500i PSU is Haswell-ready and can deliver its full power continuously at up to 50 degrees Celsius (122 degrees Fahrenheit). Strangely enough, in the protection features section, we don't see overpower protection (OPP) listed. However, we think it is present, because once we tried to overload the PSU with more than 1550W, it shut down after a while. Two major features of the AX1500i are the fully modular cabling design, which is essential in a PSU with so many cables and connectors, and the fluid dynamic bearing (FDB) fan, which is most helpful for increasing the PSU's reliability and longevity. The operation of the FDB fan is supported by a semipassive mode that can be disabled through the provided software.

The AX1500i has large dimensions and weight, which is normal, since it is a real powerhouse. However, we have recently seen some PSUs in this category with significantly smaller dimensions (e.g., the SilverStone ST1500-GS), but we should note that none of them comes close to the performance levels that the AX1500i achieves. The warranty period for the AX1500i is very long — seven years — showing Corsair's confidence in its platform. While the price is quite high, given the technology that this platform features, we believe it is justified.

Power Specifications

Swipe to scroll horizontally
Rail3.3V5V12V5VSB-12V
Max. PowerAmps30301253.50.8
Watts180150017.59.6
Total Max. Power (W)1500

The +12V rail can deliver the unit's full power alone, and this means a huge max current output that reaches 125 A. The minor rails are very strong as well, with 180 W max combined power. The 5VSB rail has enough power at 3.5 A, although, in a mega-PSU like this, we would like to see at least 4 A on this rail.

Cables And Connectors

Swipe to scroll horizontally
Modular Cables
DescriptionCable CountConnector Count (Total)
ATX connector 20+4 pin (710mm)11
4+4 pin EPS12V (800mm)11
4+4 pin EPS12V (650mm)11
6+2 pin PCIe (700mm+150mm)24
6+2 pin PCIe (800mm)22
6+2 pin PCIe (650mm)44
SATA (550mm+100mm+100mm+100mm)28
SATA (500mm+100mm+100mm+100mm)312
4 pin Molex (450mm+100mm+100mm+100mm)312
FDD adapter (+100mm)22
PMBUS cable (+800mm)11
USB Mini to Motherboard Header cable (+800mm)11

The AX1500i comes with a multitude of cables, including 10 PCIe connectors, 20 SATA connectors and 12 peripheral connectors. Essentially, you will be able to power everything with this unit. In fact, we don't remember any other PSU having this many SATA connectors, so if you want to build a file server, this looks like the ideal PSU to power it. As you can see from the last two rows of the table above, Corsair also provides the suitable cables that will allow you to connect this unit either to a Corsair Link Commander or directly to a USB header on your system's mainboard.

Overall, cable length is satisfactory, but we would have liked the four-pin Molex connectors to be farther apart, since usually, the components that are fed by these connectors are not close to one another. Finally, the 24-pin ATX connector and all EPS and PCIe connectors use 16-AWG wires for lower voltage drops at high loads, whereas the rest of the gauges are 18 AWG.

Power Distribution

Through the Corsair Link application, you can enable overcurrent protection (OCP) for each of the 10 eight-pin sockets onto which the PCIe and EPS cables are attached. This means that power distribution is optimal, and you also can set a custom OCP level, with the maximum being 40 A for each of the virtual rails.

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Aris Mpitziopoulos
Aris Mpitziopoulos
Contributing Editor

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

14 Comments Comment from the forums
  • Nuckles_56
    For such an expensive unit, why on earth did they put the CapXon caps in rather than a complete set of Japanese ones?
    Reply
  • basroil
    Wow, this thing has almost as good of regulation and transient responses as the Seasonic 660XP2! And at 1500W no less... Might be a good PSU for not just 4-way K80 workstations, but also powering 12VDC robots too!
    Reply
  • mctylr
    Corsair's flagship power supply unit (PSU) offering, the AX1500i, is the best PSU money can buy today, according to many experts in the field.

    Honestly?! Do you believe that anyone can reasonably assume that this is an impartial, unbiased review when that is the review's opening?

    Argument from authority (or appeal to authority) isn't what I expect from a Tom's Hardware review.
    Reply
  • Bossyfins
    Corsair's flagship power supply unit (PSU) offering, the AX1500i, is the best PSU money can buy today, according to many experts in the field.

    Honestly?! Do you believe that anyone can reasonably assume that this is an impartial, unbiased review when that is the review's opening?

    Argument from authority (or appeal to authority) isn't what I expect from a Tom's Hardware review.


    He said to many others in the field. Pretty sure he is not implying himself.
    Reply
  • jimmysmitty
    16665297 said:
    For such an expensive unit, why on earth did they put the CapXon caps in rather than a complete set of Japanese ones?

    They are polymer caps, as mentioned, which might not make a difference even if they went with Japanese caps. In fact looking at the results even some that probably have all Japanese caps got beaten in many areas.
    Reply
  • Eggz
    Good review, but please do something about the large arrows blocking the garphs' labels. I can't read what the data actually presents with that info blocked.

    As for the actual unit, we know it's good. This thing's been out for about a year now. We at least now have conformation from a pretty reliable source, so thanks for that!

    And for this:

    Argument from authority (or appeal to authority) isn't what I expect from a Tom's Hardware review.

    What is wrong with appealing to authority? I don't know astrophysics, but I can tell you something about it if an astrophysics professor tells me about it. And how would the professor learn his basic knowledge before becoming a professor? Text books, probably. Who wrote those? Ah, yes authorities in the field!

    Dismissing references to authorities, as a non-expert, is stupid. It's essentially saying "Since this person has dedicated his (or her) entire life to researching this topic, I will definitely make up my mind on that topic without considering what he (or she) has to say about it." That falls right under the definition of intentional ignorance.

    To be fair, though, the article didn't cite to an actual authority. It assumed that the readers will have familiarity with other rigorous review sites like Jonny Guru, who reviewed the AXi1500 back in April of 2014, giving it the only 10/10 ever with the following comment: http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story&reid=378

    I was starting to think nobody would ever send me a unit good enough. People, THIS is what it takes to get a perfect total score from me. Might be the last time you see it, too. Goes without saying I need to slap in that good old recommended logo right here

    Reply
  • mctylr
    16667641 said:
    Argument from authority (or appeal to authority) isn't what I expect from a Tom's Hardware review.

    What is wrong with appealing to authority? I don't know astrophysics, but I can tell you something about it if an astrophysics professor tells me about it.
    Dismissing references to authorities,

    Argument from authority is not about presenting or relaying knowledge from a known authority, but the premise that the argument(*) should be accepted on the basis that it came from an authority, not that the argument should be evaluated and (conditionally) accepted based on its own merit.

    (*) or in this context a review
    Perhaps I was sloppy in my usage. My concern is that by making such a reference to unspecified experts' opinions, introduces a potential cognitive bias, namely that the reviewer (Aris) expected the review unit to perform to those expectations, and not necessarily report with an impartial review of the unit as received and as actually measured.

    While I assume the power supply is of excellent quality, and I have no reason to expect any intentional or deliberate wrong-doing, the opening of a review with such a reference of praise, suggests that they reviewer could be subtlety influenced by these expectations during the review process.

    In my opinion such a reference to other reviews / opinions does not belong in a review introduction, but if mentioned it should be brought up during the conclusion of the review.
    Reply
  • Amdlova
    I see some corsair s... inside its not better than an evga power, Seasonic all for the win!
    Reply
  • iam2thecrowe
    16667294 said:
    16665297 said:
    For such an expensive unit, why on earth did they put the CapXon caps in rather than a complete set of Japanese ones?

    They are polymer caps, as mentioned, which might not make a difference even if they went with Japanese caps. In fact looking at the results even some that probably have all Japanese caps got beaten in many areas.

    Here's some opinions of capxon caps: http://www.badcaps.net/forum/showthread.php?t=20979
    I know I wouldnt trust them, have seen too many blow, and theres really no reason to cheap out on such a high end psu. But, the reason they used them may have been due to sizing, availability of those specs or something else....... They might measure well when theyre new, but will they last?..... This is something a review can never tell us unfortunately. I guess as long as theyre rated generously, they should be ok, polymer caps will have much less tolerance to overvoltage.
    Reply
  • Eggz
    16668249 said:

    My concern is that by making such a reference to unspecified experts' opinions, introduces a potential cognitive bias, namely that the reviewer (Aris) expected the review unit to perform to those expectations, and not necessarily report with an impartial review of the unit as received and as actually measured.

    That's a fair concern generally, but the reasons giving rise to it seem misplaced. The particular place in a review that someone gives praise - beginning, middle, or end - doesn't make much of a difference for anyone who edits their writing, which I'm sure this reviewer does. It's actually good practice to open with lessons learned for this type of article; otherwise, the piece would be meandering and simply take readers through the experimentation process in real time. That's boring and would probably decrease readership.

    As for whether to mention (or allude to) other reviews at all, I am not sure it's a good idea for Tom's reviewers to intentionally ignore other reputable reviewers. In all likelihood, many of them are acquaintances from various trade shows. But more importantly, I'd expect a Tom's reviewer to have read all other serious reviews before writing his own. Without doing that, they'd run the risk of writing repetitive information, or worse, writing a less informative review than others currently available. Being familiar with the work of others in your field is part of what builds credibility.

    I'm not trying to say that we should pretend Tom's is immune to fallacious logic. It's good to think about those things. My point is just that it didn't seen to present a real problem here.
    Reply