Thermaltake London 550W Power Supply Review
Ryan Martin / 10 years ago
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 | 12 | 10.4 | 12.8 |
| 40 | 15.2 | 13.2 | 15 |
| 60 | 16.8 | 16.4 | 26.6 |
| 80 | 18.4 | 18.6 | 32.4 |
| 100 | 20.4 | 23.4 | 44.8 |
Ripple suppression was good across all rails; less than 25mV on the 3.3 and 5 volt rails and less than 50mV on the 12 volt rail is a strong result for this price point. Better performance can be had on other units, such as Seasonic or Super Flower ones, but generally speaking these units will be more expensive or have lower efficiency to meet the same price point.
3.3 volt @ 100%
5 volt @ 100%
12 volt @ 100%
