Corsair AX750

With sales of around 150,000 PSUs a month, Corsair is one of the largest vendors for retail power supplies. Corsair got in earlier than most other lateral entrants like GeIL or A-DATA, and their time in the market has enabled them to gather a lot of experience even if they don't have their own factory. In recent times they've used CWT, Seasonic and Flextronics as their PSU ODMs.

A few weeks ago Corsair presented their newest PSUs, the AX series. The goal is to provide performance, quality and high efficiency, this is apparently the best power supply Corsair can offer at the moment. Today we'll look at the AX750; is the 80Plus Gold certificate justified? And what other useful features does it provide?

The AX750 and 850W models are based on a Seasonic design (X-400FL and/or X-760) with some modifications in the details. For example Corsair uses flat peripheral cables and offers a 7-year warranty. They don't have the PWM fan from the original (it's an Antec patent), but they use the same kind of fan regulation; we will see that later in our test. Interesting features include the fully modular cable management and a silent, semi-passive fan control. Here's a complete rundown of the features (and marketing material).

Corsair Professional Series Gold AX750 features:

  • Supports the latest ATX12V v2.31 and EPS 2.92 standards and is backward compatible with ATX12V 2.2 and ATX12V 2.01 systems
  • An ultra-quiet 120mm double ball-bearing fan delivers excellent airflow at an exceptionally low noise level by varying fan speed in response to temperature
  • 80 Plus Gold certified to deliver at least 90% efficiency at 50% load
  • Active Power Factor Correction (PFC) with PF value of 0.99
  • Universal AC input from 90~264V
    • No more hassle of flipping that tiny red switch to select the voltage input!
  • A dedicated single +12V rail offers maximum compatibility with the latest components
  • Over-voltage and over-current protection, under-voltage protection, and short circuit protection provide maximum safety to your critical system components
  • High-quality Japanese capacitors provide uncompromised performance and reliability
  • Completely modular cable system allows you to use only the cables you need
    • Power supply upgrade and replacement is easy, as the cables only need to be disconnected at the power supply
  • Low-profile, flat cable design reduces air friction and helps maximize airflow through your computer's chassis
  • A seven year warranty and lifetime access to Corsair's legendary technical support and customer service
  • Dimensions: 150mm(W) x 86mm(H) x 160mm(L)
  • MTBF: 100,000 hours
  • Safety Approvals: UL, CUL, CE, CB, FCC Class B, TÜV, CCC, C-tick

The 750W version is currently on sale for $150 online, with an additional $20 mail-in rebate. That's not too shabby, considering the older Seasonic X-750 still costs $170. However, we'll need to see if the quality of the AX750 matches the X-750 before we can determine if the reduced price makes this a better buy.

Package Contents and Power Rating
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  • TheShortOfIt - Tuesday, November 30, 2010 - link

    Well the AX750 is a great PSU.. I bought it in Germany for 135,- EUR cheapest price on internet... thats 175 US$ - lol.. If I would get them for 115$ - I would buy a second one as spare :D -
  • iamkyle - Tuesday, November 30, 2010 - link

    Any chance we could get the efficiency and regulation levels in a comparison bar graph like some of the other sections? It would be so much easier to compare the PSU with some of the other units that AT has reviewed in the past!
  • King.Koba - Tuesday, November 30, 2010 - link

    The best deal for a quality 80 Plus Gold PSU atm is the Seasonic X-750 which is on sale for only $120.
  • King.Koba - Tuesday, November 30, 2010 - link

    I meant to say X-650*
  • Phoenixlight - Tuesday, November 30, 2010 - link

    "A few weeks ago Corsair presented their newest PSUs, the AX series"
    More like a few months ago...
  • yati - Tuesday, November 30, 2010 - link

    I have been running a AX750 for about a month now. It is awesome. I have an oscilloscope and have test some basic parmeters. Ripple and voltage is almost identical to Anands.
    This PSU is a very good deal when you factor in:

    1) Gold Cert. Efficiency
    2) Nice all black cables, no rainbow colors cables sticking past the sleeve like other power supplies.
    3) The $20 rebate that has floating around.
    4) The insane 7 year warranty that even Seasonic doesn't offer.

    I don't know why some people get all butt hurt when they already own a X-750 or HX850.

    Both are great PSU. Almost all PSU from Corsair or Seasonic are winners.

    That other guy getting technical that the AX750 is not "the best" compared to the AX1200 is a nut head. AX series is suppose to be Corsairs top of the line series. Tx , Hx, then Ax. Is it better than a HX850? Yes in some areas and no in others.
  • iamezza - Wednesday, December 1, 2010 - link

    I think the main reason we don't see more high-quality, high-efficiency PSUs that are lower power is because it's much harder to make a low power PSU that is very efficient at lower loads.

    And it's kind of ironic because the 80 plus standard is there to try and encourage efficiency but the standard mandates that the PSU has to be very efficient at 20% load. For a 750W this is a quite reasonable 150W load, but for a 400W PSU this is a very low 80W load. It's ironic because if we could actually buy lower power PSUs they would actually be more efficient for most PC's because most PC's don't need more than 250W-300W max.
  • PeterSF - Wednesday, December 1, 2010 - link

    I was looking at Newegg's deals on PSU's last Friday, and saw the X750 with the previously mentioned $20 discount at $169.99, but they also had a promo code for an extra $50 off (no longer valid).
    The Corsair in this review is based on its successor, the X760, as stated.

    Researching, it seemed like many people thought the X750 was the best 750W PSU out there. Granted it's about to be succeeded by the X760, but for $120 with promo it was a steal, and I was surprised it didn't sell out at that price.
    UPS just delivered it and I'll be opening the box next.

    Like this reviewer, and another said, 750W should be adequate for even crossfire or SLI rigs, although I wouldn't try to drive 2 GTX 580's with it.
    I have 3 Seasonics now, including a 330W and my main rig's modular 500W; neither have ever let me down. Also a Silverstone silent 300W I bought a while ago, which I may use again in an HTPC.

    Apparently the X750 is silent before reaching a certain power draw, as the Sanyo Denki PWM fan doesn't even spin at low loads. Some people think it is defective for this reason, and one even RMA'd it before realizing his mistake.

    I found a handy tool to calculate your PSU requirements here (not sure if links are allowed as it's my first post) but google PUSengine and you'll find it.
  • ruzveh - Wednesday, December 1, 2010 - link

    To the writer,

    I dont know whether the following test is true or not. Most of the website that has tested This AX Gold series PSU shows efficency reaching 93% in some cases and only in one case the efficency drops to below 90% in their AX850. Now i really dont know whether this is the fault of 750 that it is falling below 850model or ur test is wrong. I request u to Please test the AX850 model to get the clear picture overall.. I recently bought this AX750 bcoz saving elec. is my duty towards nature :)
  • Martin Kaffei - Thursday, December 2, 2010 - link

    I'm not sure which tests you are talking about, but our measurements are correct. The measured value is relative to the test methodology. It depends, if you use a Chroma, SunMoon or PC; 20°C, 25°C or 50°C; ATX loads or more on the +12V rail and so on.

    Even if everyone would use the same chroma with the same temperatures it depends, how many cables there are from the PCB to the testing station. Fox example jonnyguru measured only 89% at 115VAC, while we had more than 90% with the same power grid.

    In addition we didn't show every decimal place. The maximum efficiency is a little bit over 91%, so we are very close to other tests.

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