Package Contents and Power Rating

There are a few extras in the package, which is typical of high-end PSUs. Included are several cable ties, mounting screws, the power cable, and a users manual, plus a couple of cloth bags that can be reused. On the package we can see that the AX750 is EuP-ready (low power loss in standby mode) and is a compact design measuring 160mm including the modular connection panel. Their reviewer's guide suggested we look at efficiency at 50% load, where the AX750 will be at the maximum 90% or greater level, but we'll also look at how it handles lower and higher loads.

Here we have an external impression of the Corsair model. The Case has a black, scratch-resistant surface with a Corsair logo on both sides. It has honeycombed ventilation holes and a small power switch near the AC plug. It's a very well-made product, with our only complaint being that the fan grille protrudes a little.

Corsair uses a single +12V rail that nearly delivers the full rated power. The AX has DC-to-DC for the smaller rails, so +12V feeds +3.3V/+5V and you can't use the whole 62A there. Even so, Corsair wants to supply modern components with plenty of juice, and 744W minus (up to) 125W is still a good rating. As you can see on the label, 100-240VAC and 50-60Hz are no problem for this PSU. The Corsair AX has active PFC, and we've tested the efficiency and PFC on both power grids.

Corsair AX750 Cables and Connectors
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  • Nentor - Tuesday, November 30, 2010 - link

    "Besides, as we pointed out on the noise tests, the hardware required to even push a 750W PSU to the limits is such that you're likely to idle closer to 150W (or higher)."

    I am also on the lookout for a high quality build PSU and this point interests me.

    Why do these high quality psu always start at around 750W? PSU work most efficient around 50%, as the results in this article also show, so why aren't there any smaller rated ones since idling with it is the most you will be doing?

    What about "no-load protection"? When will it kick in on these high end psu?

    I probably idle around 120W and wonder if it would be better for the PSU if it has a higher load to work with (relative to its maximum) than almost nothing.
    Reply
  • HangFire - Wednesday, December 1, 2010 - link

    >Why do these high quality psu always start at around 750W?

    There are high quality PSU's less than 750W, such as the Seasonic Seasonic SS-560KM 560W. These rarely get reviewed, or submitted for review. Major retailers rarely stock them, especially under 400W. Why? It is a difficult value proposition to get someone to buy a 350-500W power supply for over $100, even though build quality, ripple performance, and hold-up time justify that cost.

    The average gamer who just had a 400W cheapie burn out (because it can only produce 200W), then a 800W cheapie burn out (because it could only produce 300W), is finally ready to spend real money for a real power supply. He or She wants 1000W AND quality this time, because clearly 800 (psuedo-)Watts cannot handle a 3.4GHz 920 and single GTX480. But, the gamer cannot afford both Quality and 1000W, so the gamer "takes a chance" with a quality power supply at "only" 750W. Of course, once real quality enters the equation, 600W would be overkill, but that lesson hasn't been learned yet.

    >I probably idle around 120W and wonder if it would be better for the PSU if it has a higher load to work with (relative to its maximum) than almost nothing.

    The primary difficulty with low-load efficiency is that the 80+ organization doesn't test it, so it doesn't factor into the design because there is no reward for it. The larger a power supply is, the higher wattage the first tier of 80+ testing, since it is percentage based.

    A consumer truly concerned with their power bill will purchase a Bronze or Silver with the minimum Wattage rating for their system, rather than a Gold 750 with 400W of excess power. However that is still a difficult value proposition to risk-adverse gamers who have had hardware smoked by the ubiquitous featherweight 400W PSU that came with their first gaming case. For them, excess wattage is insurance.
    Reply
  • janwuyts - Tuesday, November 30, 2010 - link

    If I compare with your Enermax review from january (http://www.anandtech.com/show/2920) its seems that one is still the better choice no? (quieter and slightly more efficient) Reply
  • Martin Kaffei - Tuesday, November 30, 2010 - link

    Hi,
    well, the Enermax article was written by another editor.

    In my opinion Corsair (Seasonic) is better because of very low ripple & noise results, the full modular connection panel and more SATA connectors than the Modu87+ 700W.
    In addition Corsair is cheaper than Enermax and Seasonic.

    Efficiency is not everything, but you are right. Enermax has some advantages too.

    Like the very silent fan control (with a separate supplied hall IC).
    Reply
  • JPForums - Tuesday, November 30, 2010 - link

    From the article: It would be nice to see some other brands or types; however, all parts are high-quality.
    (Trying to use quotes causes errors on post)

    Why other brands?
    Is Nippon Chemi-Con not up to snuff?
    You claim they are high quality parts.
    The unit is cheaper than its Seasonic counter part, so I doubt cost is the issue.

    Why other types?
    is there a flaw in this power supplies regulation that would be better served with different parts?
    Perhaps there is some other undisclosed reason for your comment. (I.E. Brand Preference)

    I'm simply confused as to what information I should be taking away from the above comment.
    Is it a subtle hint that Corsair could have done better, perhaps a poorly worded comment that you often see more variation, or something else entirely?
    Reply
  • scook9 - Tuesday, November 30, 2010 - link

    You mention several times in the article that this is the best Corsair has to offer and I am going to have to disagree......perhaps you meant this family? There is also the AX850 and AX1200.

    I personally have an HX850 right now and if I ever find the need to upgrade it will be to an AX1200 for sure. That PSU is a MONSTER in both quality and capability. The fact that the AX1200 is less than a cm longer than my HX850 is also AWESOME considering how big alot of competing 1kW+ PSUs are these days
    Reply
  • JarredWalton - Tuesday, November 30, 2010 - link

    The AX series as a whole is Corsair's current top-end PSU, yes. We only looked at the smallest entrant in the AX family, but it's reasonable to expect similar quality on the higher capacity models. Still, you'd be pretty hard pressed to fully load 750W, let along 850 or 1200W. Reply
  • landerf - Wednesday, December 1, 2010 - link

    The AX line isn't all made by the same oem. I'd reword the whole this is the best part. You want to see the best, review the AX1200. It's godly. Also worth noting that quality wise the 850HX beats out a few of the AX models still. I think there's 3 oems for both the HX and AX lines so it's a bit complicated. Reply
  • JarredWalton - Wednesday, December 1, 2010 - link

    True there's more than one ODM involved with making the AX series. Seasonic is the ODM for the AX750 and AX850 I believe. The "best" is also up for debate I suppose, but HX850 is 80 Plus Silver and AX is 80 Plus Gold, so in that sense at least it is their "best". Martin is working on a roundup of 1000W+ PSUs, so I'm not sure what's in there but for the uber-PSU folks we have something coming.... Reply
  • HangFire - Wednesday, December 1, 2010 - link

    All *X series Corsair PSU's are positioned as high-end, versus the -S "gamer" series. The primary difference between AX, TX, and HX is AX is Modular, TX is non-Modular, and HX is semi-Modular.

    Of course, there are other differences including OEM and 80+ ratings, especially as some models are older than others. Expect more Gold out of TX and HX lines (or their replacements) as new models supersede old.
    Reply

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