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Seasonic X-750: Results

Roundup: 12 Gaming Power Supplies Compared
By , Patrick Afschar

Efficiency meets 80 PLUS specifications:

Efficiency under different load profiles:

The PSU fares well in the efficiency measurements, although it only just reaches the required values for the 80 PLUS Gold certification. The results at given loads are impressive. Even at a very low 25 W, the Seasonic X-750 still achieves an efficiency of more than 70%. At 50 W, the efficiency is already up to 78%. In the other tests, the PSU ends up somewhere in the middle, except for not quite living up to the ATX specification regarding the hold-up time. The ripple and noise test results are remarkably good, with the Seasonic X-750 running well within the limits at all voltages. The engineers at Seasonic have ripple under control, and on the 12 V rail in particular.



The bottom line is fairly positive with the Seasonic X-750 scoring great results in our efficiency tests. The supply is not without weaknesses, though. Seasonic is generous with its eight Molex and nine SATA connectors, as well as with the three CPU connectors.

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  • -4 Hide
    FLanighan , December 30, 2010 3:29 AM
    Why not Corsair? I jizz at my tx850w :) 
  • 2 Hide
    xxsk8er101xx , December 30, 2010 3:38 AM
    Because it failed a few of the tests.

    FLanighanWhy not Corsair? I jizz at my tx850w

  • -3 Hide
    p1n3apqlexpr3ss , December 30, 2010 3:40 AM
    Corsair has a gamer series... whyd they test one of the units from the top line aimed more at enthusiasts?
  • -4 Hide
    V8VENOM , December 30, 2010 3:45 AM
    Odd, why isn't Silverstone reviewed at all? Most of the power supplies they looked at are junk for anyone with more than one GPU and overclocking. I dumped my PC Power & Cooling 1000 Watt PSU because it couldn't handle two ATI 5870's and overclocked CPU to 4Ghz with 1600 FSB. I put in a Silverstone 1500Watt PSU and my system has been rock solid ever since.

    The article doesn't appear to measure noise from during switching and how much noise is introduced to the CPU and bus.

    Anyway, it will be a cold day in hell before anyone gets me to switch out my Silverstone 1500 Watt PSU.
  • 6 Hide
    scook9 , December 30, 2010 3:48 AM
    V8VENOMOdd, why isn't Silverstone reviewed at all? Most of the power supplies they looked at are junk for anyone with more than one GPU and overclocking. I dumped my PC Power & Cooling 1000 Watt PSU because it couldn't handle two ATI 5870's and overclocked CPU to 4Ghz with 1600 FSB. I put in a Silverstone 1500Watt PSU and my system has been rock solid ever since.The article doesn't appear to measure noise from during switching and how much noise is introduced to the CPU and bus.Anyway, it will be a cold day in hell before anyone gets me to switch out my Silverstone 1500 Watt PSU.

    You are either lying or very unlucky (got a bad PSU)......I have crossfire 5870s and an i7 965 and all stock cannot exceed 650W at the wall (about 550W actually used) no matter what I try.
  • 5 Hide
    JamesSneed , December 30, 2010 3:50 AM
    Nice tests but I came to a different conclusion. The seasonic X-750 is close to the most effiecent in the bunch and did you see that voltage ripple it looked like it was flat lining.
  • 1 Hide
    boiler1990 , December 30, 2010 3:53 AM
    For the ~$20 price difference between the Corsair 850HX and the AX850, I think I'll get the AX. It never hurts to invest in a great PSU :) 
  • 6 Hide
    juuh , December 30, 2010 4:59 AM
    V8VENOMOdd, why isn't Silverstone reviewed at all? Most of the power supplies they looked at are junk for anyone with more than one GPU and overclocking. I dumped my PC Power & Cooling 1000 Watt PSU because it couldn't handle two ATI 5870's and overclocked CPU to 4Ghz with 1600 FSB. I put in a Silverstone 1500Watt PSU and my system has been rock solid ever since.The article doesn't appear to measure noise from during switching and how much noise is introduced to the CPU and bus.Anyway, it will be a cold day in hell before anyone gets me to switch out my Silverstone 1500 Watt PSU.


    I call BS. I could run your setup with my PC power & cooling 750w unit.
    http://www.techspot.com/review/289-geforce-gtx-480-sli-versus-radeon-5870-crossfire/page9.html
  • 6 Hide
    vanhalen , December 30, 2010 5:12 AM
    No recommendation for the Seasonic? Am I missing something?
  • 4 Hide
    random1283 , December 30, 2010 5:49 AM
    agreed no reccomendation for an x series seasonic, you guys must be mssing something, every other review of the x series said that they are simply amazing much better then any nxzt or anything.
  • -1 Hide
    dEAne , December 30, 2010 7:55 AM
    Very useful article, thank you so much tomshardware.
  • 2 Hide
    buzznut , December 30, 2010 8:37 AM
    Yeah thanks Toms, this is a timely article considering the new CPU's and motherboards coming in the next 6 months or so. Lots of us are contemplating upgrades or complete overhauls soon!
  • 0 Hide
    buzznut , December 30, 2010 9:00 AM
    BTW, it would be helpful to know exact cable lengths. There is some speculation about which models have decent cable lengths but nothing specific.

    My next build will be in an NZXT full tower, and I am particularly interested in the Antec 850W, which I believe is the same line as the 750 tested. The report mentioned something about the cables being a bit short for full towers, I'd like to know exact cable lengths, and does anyone know if the 850W model cables may be a little longer?
  • 6 Hide
    KT_WASP , December 30, 2010 9:11 AM
    Huh?

    You're kidding right? You mention the NZXT power supply as "being one of the best", but no mention or recommendation for the Seasonic (even tough according to your own tests the Seasonic handily beats the NZXT)?

    Seasonic is one of the, if not thee, best power supply houses in the land. Most of the times if you see a real good power supply from another brand, it turns out it was a Seasonic unit. I'm not saying there are no other good manufacturers out there... But, to not even to get a nod or anything in the conclusion??

    Review fail.
  • 3 Hide
    Olle P , December 30, 2010 10:12 AM
    I fail to see how a low airflow temperature is good. To me it shows that either the fan is running too fast, producing unnecessary noise, or the really hot spots don't get sufficient cooling (with most of the air passing through the PSU without touching any heated surface).
  • 1 Hide
    hardcore_gamer , December 30, 2010 11:40 AM
    Did you test the ripple when the PSU is loaded ? Ripple factor is a function of load
  • 3 Hide
    Onus , December 30, 2010 11:58 AM
    "In the remaining tests, Cooler Master's GX 750...does mess up a bit with the ripple and noise though, giving us a reading on the 3.3 V rail that is 50% above the ATX specification limit."

    So, essentially it will pick away at your RAM. No thanks.

    "...its single +12 V rail (preferable to all of the units with dinkier +12 V output spread over multiple rails)..."

    I call BS. I'd much rather have multiple +12V rails. With OCP set appropriately, there's no issue of power being "trapped" anywhere, yet it will be safer in the event of near short-circuit conditions.

    I'll be building either a SB or BD rig for myself in late Spring or early Summer, and I already picked up the 560W model of the Seasonic "X" line for it ($71 for the one HardwareSecrets reviewed).

    Remember too, that 80+ tests at the absurdly low ambient temperature of 23C. While I think their tests are still generally valid, and will certainly clear out the liar-labeled units, for a certified unit to fail by a couple percent under real world conditions is not too unusual.
  • 2 Hide
    Gulli , December 30, 2010 12:35 PM
    I'd rather see a comparison between PSUs at the lower end of the spectrum. I can't imagine any of these 750-850W monsters breaking a sweat even with dual high end GPUs. It's uch more interesting to know what's the smallest PSU that can do the job for most desktops. For example: I've been running an HD 5870 with an overclocked Core i7 920 for over a year now on a Corsair 520W PSU, with no problems whatsoever. But if I were to ask on the forums what PSU I would need for my setup most people would recommend 650W, at minimum. So please do a comparison that shows how few watts is enough for single GPU setups and which PSUs are reliable enough.
  • -8 Hide
    santiagoanders , December 30, 2010 12:36 PM
    There are power supply fanbois now? Your beloved Seasonic wasn't recommended so you rant?
  • 2 Hide
    jimishtar , December 30, 2010 12:36 PM
    To me, having bigger temp difference between input/output air is a good thing. It means the psu has good layout and the heatsinks & fan do their job. Low heat output means bad-cooling-efficiency. Every psu generates heat - not every psu deals with it.
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