The NZXT C650 650W PSU Review: Designed To Last

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.