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New PSU Causes MB alert

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  • Power Supplies
  • Components
Last response: in Components
August 24, 2005 6:15:06 PM

My old Enlight ATX 250W PS finally gave up, so I replaced it with the FSP Blue Storm 500W PS. When I tried to fire the beast up, there was a Power Management Monitor issue in the BIOS. The -5VDC line was registering -6.14V, which was apparently out of range, as it was highlighted in red. I changed the setting to "Ignore", and everything proceeded properly. My question is if this is actually a problem that I need to try to correct, or if ignoring the situation is acceptable. I can't remember the MB model, but it is an ASUS board (K7V, perhaps?) with an ATHLON Thunderbird 1200 and I believe it has a Via VT133A chipset.

TIA,
Kenny

More about : psu alert

August 25, 2005 2:27:07 AM

I would make a note of it. As you know, modern mobo's discard negative voltages. But the -5DVC line's out of range, and it's part of the ATX specification. Having said that, be weary of your system performance. If your computer chugs along without a hiccup, all is fine.
August 25, 2005 7:52:39 PM

I have had the same problem with an upgrade power supply from Antec. Strange, even the volage of -6.14V.

I gave Antec a call and they explained why. The new ATX 2.0 Standard removed the -5V reference signal from the motherboard connector. So the voltage is just floating.

From the best I can tell so far from researching this, is it is not a problem. Nobody was really using the -5V so Intel removed it from the new ATX 2.0 standard.

Here was the exact reply from Antec...

The SP-400 is an ATX12V v2.0 power supply. Our power supplies and encosures are manufactured to the Intel Standard. For the ATX12V v2.0 standard, the -5V rail has been removed because it is no longer needed. That is why you will notice a missing wire in the motherboard connector. You will find this missing WHITE wire on older power supplies. For more information, you can take a look at the Power Supply Design Guide here: http://enhanceusa.com/documents/atx12v_v2.01.pdf. Your system should work fine without the -5V rail.