![[H]ardOCP](/images/blank.gif){kind=small}
- Date:
- Wednesday, May 23, 2007
- Author:
- Paul Johnson
- Editor:
- Kyle Bennett
- Google +1
450w-500w PSU Battle Royal
You guys asked, "What about regular mid-range PSUs?" So we bought five power supplies and then tested them to see if they would do what they were advertised to do. A melting fiery mess proves you get what you pay for. 5 PSU enter, 1 PSU leave.
Ripple and Regulation 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 Apevia ATX-AS500W-BL. 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
This image is the blank background control test on an unused connector from our SM-8800 during the Apevia ATX-AS500W-BL testing. This lets us determine what the background noise looks like during testing. If at anytime 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
Test #1 is equal to approximately 25% of the rated capacity of the Apevia ATX-AS500W-BL at 45c. This makes Test #1 equal to 135w by loading the 12v rails to a combined 8a, the 5v rail to 3a, the 3.3v rail to 3a, the +5vsb to 2a, and the -12v to 0.5a. The results of Test #1 are very good. The amplitude of the traces on all rails is within specifications with only the 5v rail being a little active, but within specifications by a wide margin.
Test #2 is equal to approximately 50% of the rated capacity of the Apevia ATX-AS500W-BL at 45c. This makes Test #2 equal to 241w by loading the 12v rails to a combined 16a, the 5v rail to 5a, the 3.3v rail to 5a, the +5vsb to 2a, and the -12v to 0.5a. During Test #2 all the traces, except for the 3.3v, increased in amplitude but the unit is not even approaching the limits of the specifications. This is very good given how poorly the unit was doing in the load testing portion of testing at this load.
Test #3 is equal to approximately 75% of the rated capacity of the Apevia ATX-AS500W-BL at 45c. This makes Test #3 equal to 353w by loading the 12v rail to 24a, the 5v rail to 8a, the 3.3v rail to 9a, the +5vsb to 2a, and the -12v to 0.5a. Test #3 sees the amplitude of the 12v and 5v traces jump to life. While the 12v traces are within specifications the maximum peaks on the pulses in the 5v rail are pushing the specifications very hard if not exceeding them.
Through Test #1 and #2 the Apevia ATX-AS500W-BL did an exceptional job. However, during Test #3 the wheels began to come off as the 12v traces amplitude jumped sharply while the 5v trace jumped to the edge or slightly out of the specifications. As was noted in the load testing portion the unit was already out of ATX specification during Test #2 and #3 so the very good ripple/noise during Test #2 ends up being a moot point. Hopefully, the next power supply, the FSP BlueStormII, will do better than the Apevia.