Internal Design and Components

The interior has many indicators that this is a Seasonic-made power supply. First, there is only one DC-to-DC PCB for +3.3V and +5V instead of two. We saw this in the M12D 850W. Furthermore, the filtering behind the entrance is almost identical to the S12D design.

Interesting to note are the two different solder points for +12V. At one point we can find yellow and black cables and a "12V2" silkscreen on the PCB—just like the S12D design. That means this isn't a real single-rail PSUm and in fact most PSUs aren't multi-rail designs. Instead, they share the current between more than one output rail. That makes the design a modern version of the S12D layout. The heatsinks are smaller and the main caps as well as the DC-to-DC VRM are displaced, but otherwise they're very similar.

Transient filtering starts behind the AC inlet and continues on the mainboard. There are two X-capacitors, three coils (one is a current-compensated version), and six Y-capacitors. Six caps sounds very helpful here but we have to keep in mind that the leakage current on ground shouldn't get too high. Otherwise, we get a "dirty ground" contact that can create issues; remember that EMC doesn't necessarily equate with safety. You'll want to look at the impedance of the disturbing source, the type of problem, and the input characteristics of your power grid to choose the right components. Quantity can only be effective in combination with precision. Ultimately, having six Y-capacitors isn't a guarantee that a PSU is good PSU, but they are very good against common mode interferences. Let's move on to the power factor pre-regulator.

Here we find two GBU806 (GBU case, 8A forward) for rectifying and two very large Rubycon caps. Like nearly all modern PSUs, the TX750 has active PFC. All transistors have very common ratings so there is nothing special needed to reach 80 Plus Bronze. In the secondary circuit we find the usual five diodes in a TO-220 housing. Again there's no need for anything unusual like synchronous rectifying. The controlling circuit, incidentally, is located at the bottom of the picture, which is another modification of the M12D design. Some of those larger capacitors lean but most components are fixed well.

Appearance, Cables and Connectors Voltage Regulation and Quality
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  • Patrick Wolf - Tuesday, May 17, 2011 - link

    Agreed on power savings not being worth it. But if Platinum gives you a cooler running (less heat inside the case) and mostly silent (cause the fan stays off most of the time) power supply, then to some those are very compelling reasons to pay the premium.
  • Makaveli - Tuesday, May 17, 2011 - link

    Agree Patrick,

    This is the same reason I chose the 750AX over this model the fan being off at low load makes the system so quiet it was worth it.
  • erple2 - Tuesday, May 17, 2011 - link

    I don't know if Platinum could give you all that much in the way of a cooler case - it would, however, give you a cooler power supply. Modern PSU design has air from the case passing through the PSU and out the back of the PC.

    it doesn't matter (at least not at the differences between Platinum through 80+) whether the PSU really gets any warmer to the temps in the rest of the case, as it's all downstream of the airflow in the case, unless you reverse the fan direction to blow air into the case.
  • MeanBruce - Friday, May 20, 2011 - link

    I have heard the Platinum rating would be 92% efficiency at 50%load. Also heard that it would be 90% at 20, 50 and 80% loads, so not sure which standard was decided upon. I have the Corsair AX850 Gold and the fan never spins up during idle and running office apps, even if you put a game on the Sanyo Denki fan is so quiet it must be 10 or 12db in the silent mode. Above 50% load only then does the fan speed increase to an audible level. Another great feature of both the AX750 and AX850 is that the internal heat sinks are bonded to the exterior housing, allowing the metal psu chassis to also dissipate the heat produced and allowing the fan to remain off. And going a bit further, when I mounted the AX850 in my new Corsair 650D the metal rear and side panels surrounding the PSU become warm over extended use, so the 650D chassis also acts as a heat sink, Corsair is Brilliant!;)
  • casteve - Tuesday, May 17, 2011 - link

    Thanks for the review, Martin.

    What was the ambient SPL at the time of the test (and could you please include it with future PSU testing)? As is, we don't have a point of reference. The room could be 25dBA ambient and the PSU is lost in the background...the room could be an anechoic chamber with 11dBA ambient, making the PSU a vacuum cleaner.
  • Martin Kaffei - Tuesday, May 17, 2011 - link

    Your request will be taken into account. I can't say how much dB, but we are starting from 16 dBA when a PSU is turned off. The dB(A) measurements are an instrument to show the difference to the competitors and of course to underline the subjective results. Latter one depends on the frequency, side noises (usually at a low frequency which is why db(A) is not always the best solution here) and the guy who is testing. :)

    When I write the PSU is "relatively loud" e.g. it's a subjective opionen that the PSU is audible for me. So you can be shure it's louder than other sources of noise in the room.
  • Lithium466 - Tuesday, May 17, 2011 - link

    "Corsair uses a 140mm fan from Young Lin with a ball bearing. The product number is D14BH-12 and it takes 0.70A."

    => Yate loon fan, not Young lin.
  • Martin Kaffei - Tuesday, May 17, 2011 - link

  • mepenete - Tuesday, May 17, 2011 - link

    I've had excellent luck with Corsair powersupplies, even the lower end budget ones. I was really surprised after only knowing Corsair for memory but they make good products. Glad to see they're staying up that high standard
  • celestialgrave - Wednesday, May 18, 2011 - link

    What ever happened to measure the exhaust heat like a couple of years ago?

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