Cold Test Results

For the testing of PSUs, we are using 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.

From the above charts, we can see that the NZXT C650 meets the 80Plus Gold certification requirements when powered from either a 230 VAC or 115 VAC outlet, even if only barely. It almost missed the certification requirements at 20% load and we can see that the efficiency of the PSU plummets as the load decreases, dropping well below 70% when the load is lower than 35 Watts. When the load drops below 20%, the efficiency drops so much that the raw power losses increase – a very rare effect. Apparently, this platform is not designed to cope with loads much lower than those intended.

We tested the NZXT C650 with its hybrid fan mode disabled, meaning that the fan was running at all times. In that scenario, the fan only became noticeable when the load ws greater than 320 Watts, and remained barely audible for loads up to 450 Watts. It eventually reached 42.9 dB(A) under maximum load, a passable noise figure for most users, and a great result from a PSU that is using a 120 mm fan. Considering that a PSU should never run at maximum load for prolonged periods of time, the NZXT C650 should be unnoticeable if installed inside a well-ventilated case.

Introduction, Examining Inside & Out Hot Test Results


View All Comments

  • npz - Tuesday, August 11, 2020 - link

    I hate the PSUs that cheap out on the intake sheet metal with stamped grills. The circular holes here restrict air flow and causes more fan noise, especially at higher air flow than one using a much more open traditional wire grill. Reply
  • Arbie - Tuesday, August 11, 2020 - link

    Like every grille on every computer case ever made. And on every blower-style graphics board, where you might really think they'd do a little something extra to reduce noise. Reply
  • npz - Tuesday, August 11, 2020 - link

    First I'm specifically referring to the intake side if a fan, which when restricted, produces much more noise than on the exhaust side. Second only cheap bottom of the barrel cases use these kinds of stamped hole grills, which still restricts exhaust air flow, but the same case would probably use it on the intake sides too. You are right that they are plentiful though. However, upper end cases use separate large honeycomb shaped grills which usually protrude outwards and which provide more airflow, and the gaps of those.meshes can also differ. Some cases still use open wire grills.

    Finally regarding blower GPU cards, none of them have any grill whatsoever in front of the fan
  • Amoro - Tuesday, August 11, 2020 - link

    The main downside to this PSU is the lack of a second 8-pin for the CPU. Most X570 motherboards seem to require an 8 and a 4 pin. Reply
  • qlum - Tuesday, August 11, 2020 - link

    While they generally do have the extra 4 pin, actually plugging it in is completely optional unlike the extra connector on gpu's. In terms of power requirements it's also completely unnecessary to use it. The extra 4 pin is mostly the motherboard manufacturer showing look at our beefy vrm rather then actual need. Reply
  • MrVibrato - Tuesday, August 11, 2020 - link

    No. Your AM4 CPU doesn't require 8+4. It's called gamer street cred.


    Is it even possible for gamers to have street creds?
  • MrVibrato - Tuesday, August 11, 2020 - link

    Darn... wrong reply button... was supposed to be a reply to Amoro's post... Reply
  • eek2121 - Tuesday, August 11, 2020 - link

    I wouldn’t say most. The more affordable boards do not. My board has a single 8 pin. Anything above and beyond that is a gimmick. Reply
  • ArmedandDangerous - Tuesday, August 11, 2020 - link

    You only need the 1 8 pin. Anything extra is for much more exotic overclocking the majority of people will never need. Reply
  • PenGunn - Tuesday, August 11, 2020 - link

    As always, just get the Seasonic that fits your purpose. Reply

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