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Thread: Tom's Hardware view 4+4 psu

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    Default Tom's Hardware view 4+4 psu


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    Lightbulbs? As a load tester?




    Lightbulbs are ok if you want a quick & dirty test to see if a PSU functions under a load. They are not suitable for a review of any sort, which requires consistency and repeatability.

    Problem 1.) Lightbulb wattage ratings are approximate, and may vary by 10% or more from what the label says
    Problem 2.) The resistance of a lightbulb changes with the temperature of the filament, which changes with the time the lightbulb is on. If they don't wait for the lightbulbs to reach their steady state resistance, they will get faulty readings
    Problem 3.) Since resistance of the filament changes with temperature, and higher voltage induces higher temperature, the resistance will also vary with the voltage output of the PSU
    Problem 4.) They aren't loading the +5V and +3.3V rails, which means that their efficiency will be off (especially for DC-DC units) and their voltage measurements will be off (especially for group regulated units).

    All of this means that the data collected in this test is almost worthless. They also seem to think that DC undergoes "phase shift." What?


    The excessive noise in their scope readings looks like what you get when you leave off the 10uF and .1uF caps on your probe point. Since they don't document their test setup very well it's difficult to tell.

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    As far as I remember they use the lightbulbs only for the acoustic noise measurement. The rest should be chroma based. I don't remember the details.

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    there are other ways to properly measure noise (like I do) but apparently they went the easy way. Also to me you miss the whole story if you take sound measurements of only three load levels. In my recent venture in this area I managed to get sound measurements through out the entire load range of the PSU (25-26k different load combinations and readings) and make a graph of the average noise output using the appropriate algorithm.

    Check the last graph

    If I had the resources that they have I would probably build a water cooled loader, fully automated like my first one, and wouldn't go the bulbs way that looks very cheapo.

    ps. BTW there are water cooled electronic loads for minimized noise, but are pretty costy

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    Why it was titled "view" instead of "review.."

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