Internals

Opening the casing reveals a clean design with a good layout. The phase and neutral conductors as well as the transformer look undersized at first, but the new resonant topology and more active controlled parts allow the manufacturer to use smaller components. Like Seasonic, this PSU has ZVS (Zero Voltage Switiching) that reduces power loss. Moreover, the soft switching is better for EMI.

All capacitors come from Nippon Chemi-Con and there are some all solid ones in the secondary circuit, but the KMR models are a usual choice for high-end PSUs. It would be nice to see some other brands or types; however, all parts are high-quality. There is a line filtering stage in the entrance and many SMDs at the backside of the PCB. The champion IC is on a sister-PCB up top. The overall design definelty looks like an X-460FL with more caps. The only point of criticism is that the fan connector could be glued down, but that's a minor issue at best.

Cables and Connectors Noise Levels
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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. http://www.newegg.com/Product/Product.aspx?Item=N8...
  • 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.
    http://extreme.outervision.com/PSUEngine
  • 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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