Efficiency and PFC

Even at 75W (10% load) Seasonic delivers 83.43% efficiency. 115VAC reaches 89% maximum efficiency from 20% to 50% load (150W to 375W), while 230VAC delivers slightly better results as expected. Overall the X750 is as good as the Enermax Pro87+ and Modu87+ with only minor differences. If you want to save energy then the choice between Enermax and Seasonic won't generally affect the result. Instead, you'll want to look at pricing and other features.

At low input voltage, PFC starts at over 0.971 and reaches 0.993 under full load. With 230VAC the trend is lower (again as expected), starting at 0.800 at 10% load. This is still okay for the European power grid.

Cooling

Seasonic has a lot of confidence in their design and so the fan doesn't rotate at all until you hit 20% load. Thus, from 0 to 20% (150W) we have a result of 0 dB(A) on the graphs. From 20% to 50% load the X750 remains silent, but once load goes beyond 50% (375W) the fan RPMs increase rapidly. At high loads the result is more noise than the Enermax Pro/Modu97+, with a maximum noise level of over 30 dB(A). The small heatsinks and open design come into play here, as they have to compensate for the lack of surface area by pushing more air through the PSU. You can also hear the ball bearings inside the fan at maximum RPM.

X750 - Voltage Regulation and Quality X750: Potent for the Price
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  • vol7ron - Tuesday, April 13, 2010 - link

    Nice Martin, I've been looking at upgrading my PSU (550W ultra) and I only like buying the modular connectors. $200 still seems kind of high, but almost in the reasonable range. I'd like it to be $150 :)

    Another thing I might be shopping around for is a new UPS, have you guys reviewed any of those recently?
  • HOOfan 1 - Wednesday, April 14, 2010 - link

    There is a 650W version. Selling for $160 at newegg now
  • jeffbui - Wednesday, April 14, 2010 - link

    $138 at ewiz/superbiiz for the 650w version. I couldn't be happier with it.
  • vol7ron - Wednesday, April 14, 2010 - link

    I like the plan for the future though, especially with power supplies since they last long.

    My guess was that the next upgrade would be 750W or higher, the real goal was to have an 800W PSU and UPS. My machine probably only currently uses 350W, but I like to have headroom, especially since I keep adding HDs and will probably take advantage of more PCI slots in the future.
  • Souka - Wednesday, April 14, 2010 - link

    HX650 or HX750 (both are modular)

    HX650 is $120 at NewEgg, I have it... quiet and works well. Reviews show it to be 80+ Silver. but Corsair chose to be Bronze as their own testing (under very hot conditions) didn't qualify for Silver... Kudos to Corsair.
  • Souka - Wednesday, April 14, 2010 - link

    Sorry..my bad. Corsair PSU is Silver...almost Gold.

    One important thing about the HX650 and HX750 PSU is that they're just shy of 90% effecient at a VERY wide range of loading.

    True, the Seasonic unit does do better at PEAK efficiency (if using 220v) by a few %, but if you're actually going to use a 750W PSU at any other load than this, the Corsair will save you $$ upfront and in the long run with lower power bills.

    My $.02
  • HOOfan 1 - Wednesday, April 14, 2010 - link

    HX650 is bronze...nothing more than bronze

    HX750 is silver and was originally awarded Gold by 80plus.
  • Franson - Wednesday, April 14, 2010 - link

    Are you a bot or something? Take your stupid Corsair fanboyism and shove it....!!
  • Souka - Thursday, April 15, 2010 - link

    Wow... nice post...
  • piroroadkill - Thursday, April 15, 2010 - link

    The HX650 IS a Seasonic design, and I think, by looking at it, the HX750 is a Channel Well design. Regardless, Seasonic was also the OEM for the HX520 and HX620. Seasonic make damn fine power supplies.

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