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Is 11.89V on the 12V rail considered too weak?


I recently scored a Optiplex 380 to mess with from a recycling facility, and in the process of tinkering with it and getting it to the way I would like it, I found something off with the power supply

This isn't about the system, as it appears fine but I need to get a hard drive, and some memory for it since both of these items were pulled before I got it, but after I get those the machine will probably work just fine

I tried my video card I installed in this machine on the OEM 255W power supply, and I noticed it doesn't spin up too well with the 255W power supply(NPS-255BB A, N255PD- 00), yet this card span up fine on a ATX 20-pin power supply, in a board with a 24-pin connector so I thought this was a bit odd, so I switched the power supply and it worked just fine, as it did on the 20-pin supply for me

I had tested the supply's 12V and 3.3V with a power meter, and this is how it tested

  • the 3.3V tested at 3.3V, so the 3.3V rail in the supply is fine
  • The 12V tested it 11.89V of 12V, which I thought was weird

I tested another machine's 12V line around here, an I got 12V, so my multimeter wasn't lying to me about it

I tested the replacement supply, which came from a 2006 Prescott BTX Dell, and that tested at 11.95V, which seems to spin the fan a little reluctantly, but it does it much better. so apparently 11.95V is enough for the 9500GT to spin it's fan

What is everyone's opinion on 11.89V on the 12V rail on a power supply? Would you consider it too weak to use and set it aside for the bin, or keep it as a spare supply that isn't trusted and should be used with caution?

Edit-the Dell machine i have that had the .11 loss is a Optiplex 380's original 255W supply, and I yanked the 305W from the Dimension 5150(2006 Prescott, no headroom for a Pentium D model board)

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Nick, the 0.11 Volt is negligible. The 9500GT video card requires a minimum of 350W, your PSU is to small for the video cards power requirement. You did not tell us what model your BTX is. Hope this helps, good luck.

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Here's the specs on the replacement supply, and why I think it has no problem running the 9500GT and a C2D, and also ran a P4HT 630 and 9500GT-even my dad(who had the 5150) pushed it, too


Your OEM only supplies 66% of the minimum required wattage whereas your BTX is at least at 88%. Big difference and that is why I still say your PSU is to small for the video cards power requirement. This is not an issues with the 0.11 volt difference


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