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Chieftec SFX 500GD-C 500w Power Supply Review

Ripple

Noise and Ripple can easily be measured by an oscilloscope. These show how much voltage fluctuation there is on a particular rail. We tested the rail stability of the 3.3 volt, 5 volt and 12 volt rails using an identical time and millivolt scale for all graphs. millivolt ripple is measured by the peak to peak size of the voltage curve.

Sample Ripple Graph

The latest ATX 12 volt version 2.3 specifications state that ripple from peak to peak must be no higher than 50 millivolts for the 3.3 volt and 5 volt rails, while the 12 volt rail is allowed up to 120 millivolts peak to peak to stay within specifications. Millivolt figures are stated to the closest increment of 5 given their variability.

Load (%)	3.3V Ripple	5V Ripple	12V Ripple
20	7	7.8	12.8
40	8	10.4	19.8
60	9.6	13.2	27.4
80	10.4	16.2	40.4
100	16.6	22.6	55.6

Ripple was pretty good across the board. Sure, it’s a little high at 12v at 100% load, but it’s still within a safe margin and about where I expected it to be for a compact unit such as this.

3.3 volt @ 100%

5 volt @ 100%

12 volt @ 100%

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Peter Donnell

As a child still in my 30's (but not for long), I spend my day combining my love of music and movies with a life-long passion for gaming, from arcade classics and retro consoles to the latest high-end PC and console games. So it's no wonder I write about tech and test the latest hardware while I enjoy my hobbies!