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Thread: Very odd PSU problems

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    Default Very odd PSU problems

    I bought a Enhance 400W PSU the other day. Tonight I checked it with a Rexus PSU tester and all of the rails were within normal parameters (well, the -12V was at 11.91V but that is nowhere near problem territory).

    So, I plug it into my computer and just like a dead PSU, the fans only spun for half a turn and then died. The DRAM LED light on my DFI mobo was lit so the ram was getting power without a problem.

    I have tried my Truepower 450W and a GameXstream 700W and both worked without a hitch so it isn't a grounding issue or a short.

    Could the PSU tester be THAT wrong??

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    No it could be that your DFI draws too much on the 5VSB rail that it's causing a problem with your shiny new Enhance. That's the problem with the DFI, it needs 3A+ on the 5VSB rail which is well above the 2.5A in the ATX spec.

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    The 5V rail is rated to 14A and the combined wattage for the +3.3V and +5V rails are 130W. There is no WAY I am drawing that kind of power. At least not with a single DVD drive and a single HD. Plus, isn't the 3A on the DFI mobos for standby?

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    As I said 3A+ The plus is the key. Try it on another mobo and if it powers it up then you know I'm right and if not then you need to RMA it.

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    True...I may have to wait for that though.

    Can you explain how that 3A+ (or 36W) is the key? The PSU indicates that there should be sufficient power.

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    Depends upon the mobo and the PSU. DFI is infamous for playing fast and loose when they build the LP line. One board may be fine with a 2.5A 5VSB rail while the next won't work with it and yet another might need even more amperage. If your particular PSU is capable of supplying 3A period to the 5VSB rail and your mobo needs say, 3.2A on the 5VSB rail then the rail will go into over current mode and shut off and the PSU won't power up.

    My Duro 900 is suffering from a similar problem but the 5VSB rail is freaking out when hooked to any mobo.

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    Ugh.....I guess that means I will have a tear down my 3200+ machine to install this PSU.

    If the PSU is rated for 14A on the +5V rail I just can't see how this is a problem. But, then again there is the Stand By 2.5A that ids also written on the PSU.

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    Matt is referring to the 5V Stand-by current. 2A on the 5VSB is pretty much the standard. DFI people refer to this as the "cold boot" syndrome, which really is a poor excuse for some crappy engineering. This coupled with issues when the 4V MOSFET is engaged has killed many a good set of BH5.

    I lucked out with my boards though.

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    Damn.....so I guess that the 2.5A this PSU is rated for is not enough. Booo!!!

    Time to sell it after I properly test it I guess.

    Is there any way to mod the mobo (BIOS, etc) to use less 5VSB current on startup?

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