Corsair CX750 750W Power Supply Review

The Corsair CX750 is, "An ideal choice for value-conscious system builders and upgraders." So when saving a few bucks and buying a Corsair Bronze rated power supply do you still get a PSU that can deliver clean power under load? We are hoping that fewer bells and whistles does not equate to less quality in the wattage department.

continued...

Ripple Testing

Since voltage output is not the only concern when it comes to quality DC output we next examined the ripple and regulation characteristics of the Corsair CX750. We examine these points since unnecessary ripple can cause premature failure of sensitive components in a number of different PC subsystems.

The DC output quality was logged via our digital oscilloscope and the EasyScope II software package. Each divider horizontally represents 2ms while each divider vertically represents 0.05v or 50mv. The ATX specification states that a unit should remain at or below 120mV of ripple and noise on the 12v rail while under 50mV on the 3.3v/5v rails.

Control Test Graphing

Article Image

This image is the blank background control test on an unused connector from our SM-8800 during the Corsair CX750 testing. This lets us determine what the background noise looks like during testing. If at any time a trace deviates from this reading that is the noise/ripple being logged by the oscilloscope for that rail. As you can see the trace is flat and shows as a blue line obscuring the axis. If during a test the axis becomes visible but a waveform is hard to discern it is most likely due to the amplitude of the trace being small in relation to our voltage divider.

120v and 100v Input

Article Image Article Image

Test #1 is equal to approximately 25% of the rated capacity of the Corsair CX750 at 45c. This makes Test #1 equal to 182W by loading the 12v rail to 12a, the 5v rail to 3a, the 3.3v rail to 2a, the +5vsb to 2a, and the -12v to 0.5a. The results of Test #1 are starting off with 12v rail peaking at ~20mV of ripple/noise and this is followed by the 5v rail at ~15mV and the 3.3v rail at ~10mV.

Article Image Article Image

Test #2 is equal to approximately 50% of the rated capacity of the Corsair CX750 at 45c. This makes Test #2 equal to 387W by loading the 12v rail to 28a, the 5v rail to 5a, the 3.3v rail to 3a, the +5vsb to 2a, and the -12v to 0.5a. Test #2 sees some mixed results as the 12v rail is peaking at ~20mV of ripple/noise still while the 5v rail has retreated to ~10mV to hang out with the 3.3v rail.

Article Image Article Image

Test #3 is equal to approximately 75% of the rated capacity of the Corsair CX750 at 45c. This makes Test #3 equal to 560W by loading the 12v rail to 42a, the 5v rail to 6a, the 3.3v rail to 4a, the +5vsb to 2a, and the -12v to 0.5a. Test #3 sees a minor change on the 12v rail as it is moving up to peak at ~25mV in this test along with the 3.3v rail. The 5v and 3.3v rails, however, are once more peaking at ~10mV of ripple/noise.

Test #4 is equal to approximately 100% of the rated capacity of the Corsair CX750 at 45c. This makes Test #4 equal to 750W by loading the 12v rail to 60a, the 5v rail to 2a, the 3.3v rail to 1a, the +5vsb to 2a, and the -12v to 0.5a. Test #4 sees the Corsair CX750 unable to complete testing and failing once more.

Torture Test

The Torture Test is equal to approximately 80% of the rated capacity of the Corsair CX750 at 45c. This makes the Torture Test equal to 596W by loading the 12v rail to 44a, the 5v rail to 7a, the 3.3v rail to 5a, the +5vsb to 2a, and the -12v to 0.5a. The Torture Test sees the Corsair CX750 unable to complete testing and failing once more.

DC Output Quality Summary

The overall DC output quality of the Corsair CX750 is hard to judge since this unit failed load testing. The CX750 started off in decent shape as the peak trace amplitudes in Test #1 were ~20mV on the 12v rail, ~15mV on the 5v rail, and ~10mV on the 3.3v rail. During the limited testing that this unit was able to complete, the trace amplitudes increased only on the 12v rail and it ended up peaking at ~25mV. Now, since this unit failed, comparing it to other products is difficult but through the tests it had completed it was tied with the Rosewill Capstone 750W, it was doing better than the FSP Raider 750W, and it was doing better than the Antec TP-750C. However, this is all tempered by the fact that the Raider 750W was able to complete more of our testing making it a better unit and the other units completed testing cleanly making those far better units. So, while the CX750 seems like it was keeping pace with the competition, it is ultimately the worst performing product among the comparable units today and it is hard to say how it would do if it was capable of completing testing. Let's move on now to see how this all wraps up.