Cold Test Results

For testing PSUs, we use high precision electronic loads with a maximum power draw of 2700 Watts, a Rigol DS5042M  40 MHz oscilloscope, an Extech 380803 power analyzer, two high precision UNI-T UT-325 digital thermometers, an Extech HD600 SPL meter, a self-designed hotbox, and various other bits and parts. For a thorough explanation of our testing methodology and more details on our equipment, please refer to our How We Test PSUs – 2014 Pipeline post.

Honoring its 80 Plus Platinum certification, the Corsair HX750i displays outstanding performance at room temperature. The peak efficiency is 94.3% at 50% load and the average within the nominal load range (20% to 100% of the unit's capacity) is an astonishing 92.9%. The HX750i performs well under low loads as well, with the efficiency plummeting only when the load is less than 50 Watts.

The very high efficiency of the HX750i combined with the hybrid fan design allows the HX750i to operate with its fan turned off with a load up to about 300 Watts. After that, the fan will start but the power supply will remain essentially quiet with a load up to 600 Watts. Only when the load exceeds that point does the fan becomes clearly audible, yet it never reaches the point where we would consider it loud -- especially if it's housed in a closed case.

The Corsair HX750i Power Supply Hot Test Results
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  • HollyDOL - Wednesday, January 14, 2015 - link

    Please note at what input voltage were the conversion losses and efficiency measured... Usualy 230V tends to be about 2% better than 115V...
  • patrioteagle07 - Wednesday, January 14, 2015 - link

    Yup... subpar review... I don't know what I am looking at here.
  • Meaker10 - Wednesday, January 14, 2015 - link

    Would help if you read their link on how they measure power supplies rather than repeating it in every article:

    "Cold Test Results
    For testing PSUs, we use high precision electronic loads with a maximum power draw of 2700 Watts, a Rigol DS5042M 40 MHz oscilloscope, an Extech 380803 power analyzer, two high precision UNI-T UT-325 digital thermometers, an Extech HD600 SPL meter, a self-designed hotbox, and various other bits and parts. For a thorough explanation of our testing methodology and more details on our equipment, please refer to our How We Test PSUs – 2014 Pipeline post."

    (The article links it in the text) they state:

    "Our Extech 380803 power analyzer does a very good job at reporting the level of power that our PSU requires at any given time. We should note that all testing is being performed with a 230V/50Hz input, delivered by a 3000VA VARIAC for the perfect adjustment of the input voltage. Unfortunately, we cannot perform tests at 110V/60Hz at the moment, as that requires a high output, programmable AC power source. As a rough estimate, conversion efficiency drops by 1% to 1.5% when the input voltage is lowered to 110V/ 60Hz."

    So try reading a bit.
  • Samus - Wednesday, January 14, 2015 - link

    "It appears that Corsair shot themselves in the foot, as there is no reason not to prefer the AX760i to the HX750i, not even if the AX760i is selling at $184 without any rebate, let alone while it is cheaper than the HX750i."

    This is what happens when you saturate your lineup. Corsair, stop making so many god damn PSU's. You only need 3-4 Categories (80 Plus Bronze, Silver, Gold...and perhaps Platinum) and only a few models in each category. They shouldn't be dividing up the models by modular or fixed cables, either, since this creates inconsistency within the category (the modular category has various 80 Plus ratings!)

    For the 80 Plus Bronze: 400, 550, 650 watt
    For the 80 Plus Silver: 400, 600, 750
    For the 80 Plus Gold: 550, 750, 900, 1200
    For the 80 Plus Platinum: 500, 650, 800, 1000

    Currently, their lineup is:

    http://www.corsair.com/en-us/power-supply-units

    They have 8 categories with a dozen products or so in EACH of them. I don't even understand why they have non-80 plus (VS series) products being that they want a reputation of delivering high quality products.

    I didn't go to school for marketing, so I'm not an expert at this...but I question whether Corsair's marketing department went to school for marketing...their product lineup is all over the place and there is no consistency.
  • just4U - Wednesday, January 14, 2015 - link

    I'd say cut the silver out all together. Not that it matters Corsair has gotten silly with PSU pricing anyway. Their value lineup is ok but once you hit the $100 mark and on up there are very good alternatives that corsair isn't matching price wise.
  • Lukeroge - Thursday, January 15, 2015 - link

    Honestly, AXi (aside from 1500i, which is newer) is worse. It has a pretty cheap mediocre fan, and many units have an issue where the fan makes a tapping sound every 13 seconds at idle. I returned my AX760i and swapped it for an HX850i
  • StrangerGuy - Thursday, January 15, 2015 - link

    This particular model that is being reviewed cost a flippin' 140 bucks at Newgg. Do they even know how much better stuff competitors offers at $140? 850W Evga G2 made by the best consumer level PSU OEM, Superflower.
  • AnnonymousCoward - Thursday, January 15, 2015 - link

    Love the review
  • eanazag - Friday, January 16, 2015 - link

    I'm not aware of what the Corsair link USB junk does. It would help to cover that as it is a feature that not all PS's have. I'm suspecting it has been covered before in another article; linking that other article would work for me.

    Another thing I look for in power supplies is if it has two 8 pin 12V ATX CPU cables. Usually it is one 8 plus a 4+4 providing the second 8. This matters if you're going to be able to hook it up to a 2P board for servers. I like to buy power supplies I can use in a desktop or server. This feature can end up costing more like in the Antec HC gamer vs. HC Pro PS's. The Antec gamer lacks this, while the Pro is sporting it.
  • DanNeely - Saturday, January 17, 2015 - link

    Some high end desktop boards are doing 8+4 or 8+4+6 as well; unless you normally replace your PSU with each build, it's something I'd recommend getting when specing out a new PSU for a high end enthusiast system.

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