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

  • 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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