Hot Test Results

As we can see in the following tables, the NZXT C650 delivers great power quality. The maximum voltage ripple on the 12V line is 28 mV, an unimpressive figure nowadays, but less than a quarter of the ATX design guide's recommended 120 mV limit. Ripple on the secondary 3.3V/5V lines is considerably worse, reaching 28 mV on the 5V line with a recommended maximum at 50 mV. We can notice the same pattern on voltage regulation, with the 12V line very tightly regulated at 0.7% and the regulation on the secondary 3.3V/5V lines reaching slightly over 2%.

Main Output
Load (Watts) 130.6 W 326.19 W 486.33 W 647.57 W
Load (Percent) 20.09% 50.18% 74.82% 99.63%
  Amperes Volts Amperes Volts Amperes Volts Amperes Volts
3.3 V 1.78 3.33 4.45 3.33 6.67 3.29 8.89 3.27
5 V 1.78 5.05 4.45 5.01 6.67 5 8.89 4.97
12 V 9.6 12.05 24.01 12.04 36.01 11.97 48.02 11.96


Line Regulation
(20% to 100% load)
Voltage Ripple (mV)
20% Load 50% Load 75% Load 100% Load CL1
3.3V + 5V
3.3V 2% 10 16 20 22 12 24
5V 1.6% 12 16 22 28 14 24
12V 0.7% 16 20 22 28 30 20

Operation in high ambient temperatures does not affect the performance of the NZXT C650 considerably, regardless of the load. The average nominal load range (20%-100%) efficiency drops by 0.8% regardless of the input voltage, going down to an average of 89.8% (230 VAC) / 88.1% (115 VAC). There is very little change across the entire load range, suggesting that the components of the PSU are practically unaffected by the high ambient temperature. The component temperatures are high but not overly so.

As expected, the thermal control circuitry of the NZXT C650 correctly detects the high ambient temperature inside our hotbox and adjusts the fan’s speed accordingly. The NZXT C650 is not silent under these operating conditions, with the fan’s speed gradually increasing along with the load. Nevertheless, the sound pressure level tops out at just 50.2 dB(A), a figure significantly lower than what we would expect from a unit with a powerful 120 mm fan.

Cold Test Results Final Words & Conclusion


View All Comments

  • eek2121 - Tuesday, August 11, 2020 - link

    I accidentally bought a Seasonic PSU thanks to Amazon’s infuriating inability to do a proper search. Still trying to decide whether to keep it or return it. Reply
  • evilspoons - Tuesday, August 11, 2020 - link

    Small nitpick on the "Main Output" table on the Hot Test Results page. At 20% you read 5.05 V, at 50% you read 5.01 V, and at 100% you read 4.97 V. All two decimals of precision. However, at 75% load it's just listed as "5 V". Shouldn't that be "5.00"? Reply
  • fred666 - Tuesday, August 11, 2020 - link

    What's the point of being 100% modular? Is someone really going to use this without the main ATX motherboard connection?
    It looks nice in the box, but I don't see any real-world advantage.
  • eek2121 - Tuesday, August 11, 2020 - link

    The cables can easily be replaced. For example, cablemod allows you to purchase custom length cables. Also, what if a connector or cable breaks? Reply
  • Threska - Monday, August 31, 2020 - link

    I could see someone going with a shorter ATX power connector. Especially since in my case it really is a short distance and most cables are really long. Reply
  • plonk420 - Tuesday, August 11, 2020 - link

    less clutter in your case if you don't have very many components. my daily driver is a 2400G + m.2 ...and 3 SATA devices Reply
  • Lord of the Bored - Wednesday, August 12, 2020 - link

    That doesn't explain why you'd want to remove the main ATX power connector.
    I grant that there ARE some situations where you don't want the motherboard power connector, but they are very rare and the people that need them are used to "manually reconfiguring" the power supply already.
  • GreenReaper - Wednesday, August 12, 2020 - link

    You may, however, wish to replace it if the cable has been frayed somehow, or a connector broke.

    Might not happen for most people, but you'll be (relatively) glad if it does for you.
  • Arbie - Tuesday, August 11, 2020 - link

    Very important info missing from your cables chart is their lengths. At least, this becomes very important if one neglects to check it... Reply
  • Stele - Wednesday, August 12, 2020 - link

    "A trained eye will easily identify the OEM behind the NZXT C650 to be Seasonic" Ya know, it does expressly say right on the PSU label that Seasonic is the OEM... Reply

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