Our load tests utilize a couple of FAST ATE active load testers and a variety of other equipment such as an oscilloscope, power conditioner, temperature probe and a power consumption meter. You can read more about our standard testing approach here.
The tests performed are based around six conceivable setups that are out there and progressively load down the PSU up to the power supply's limits or 1000W, whichever comes first. Since our test equipment's limits equal to that of the Xigmatek NRP-MC1002, we can test it to the maximum.
There is a lot going on with this power supply, so let's take a look at the results test by test. During Test 1, things start off well with the NRP-MC1002. All of the voltages are well within ATX specifications, even if the 3.3V readings are a little higher than we would like to see. Noise on the 12V rail starts off a little rocky however, coming in at 36mV peak to peak at the lowest loads we test at. The efficiency during Test 1 was great for an 80Plus Bronze rated power supply at 84.8%.
Test 2 increases the load a bit and we start to see most things falling in line with where they should be. Voltages become a little tighter and we see an increase in efficiency up to 85.8%. The ripple on the 12V rail increases a tiny bit to 39mV peak to peak, but if the NRP-MC1002 continues to increase at this rate it shouldn't be a problem.
Test 3 loads down the power supply to about 56% of its maximum capacity. All voltages are within .01V of perfection and the efficiency increases even more to 86.7%. As with the previous test, there was a minor increase in noise on the 12V rail to 42mV, but nothing to really be alarmed at.
Test 4 is where things started going downhill, quickly. The NCP-MC1002 still has great voltage regulation at this point on both the 12V rail and minor rails. Efficiency is starting to drop as to be expected, but we are now down below where we started, down to 84.6%. What alarmed us the most was the massive increase in noise on the 12V rail. Ripple almost doubled, bringing the reading up to 83mV peak to peak on the oscilloscope. Things aren't looking good here, but we continue forward.
Test 5 almost proves to be the demise of the NRP-MC1002, but it continues to hang on by a thread. While the NRP-MC1002 continues to maintain decent voltages, its efficiency slips a little bit further down to 83.5% At approximately 88% of full load, the Xigmatek unit still has some wiggle room here for the next test, but the ripple on the 12V rail continues to skyrocket. Test 5 brings the noise on the 12V rail up to 119mV peak to peak, just barely within ATX specifications which are a maximum of 120mV peak to peak.
Moving on to Test 6, we finally see the NRP-MC1002 fall out of ATX specifications. Voltage on the single 12V rail is dropping rapidly, but still within specifications, while the minor rails see a small drop as well. The Xigmatek NRP-MC1002 barely skimps by and achieves the 80Plus Bronze efficiency rating at 82% which is the minimum value for 80Plus Bronze at 100% load. After Test 5, we knew there was a very slim chance of the NRP passing ATX specifications for noise on the 12V rail. Under full load, we see that the noise on the 12V rail goes through the roof to 154mV peak to peak.