ATX PSU -5v

Hi all

I've just replaced a failed Q-Tec psu with a Thermaltake 750w psu. The Thermaltake has n/c on pin 18 of the power connector(24 pin connector only using 20 pin part of plug) but my Gigabyte GA-81K1100 motherboard expects -5v at pin 18. All seems to be working but I'm wondering what the -5v is for and if I'm likely to come across a problem?

Thanks, Marnie
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  1. I don't know what the -5v rail is for. I'm thinking it a holdover from previous generation PSU that hasn't been elminated yet. Kinda like the floppy drive.

    My BioStar mobo (MCD 400?? or something like that) says that the voltage on the -5v rail is -65v!!!!. I've had this mobo in my HTPC for two years and it has not imploded yet.
  2. Some info:

    http://www.mini-box.com/site/power-faq.htm

    and here:

    Quote:
    The 480GX doesn't, by the way, have a minus five volt (-5V) rail. But neither do most other PSUs on the shelves these days, as I've discussed before. -5V was removed from the spec as of ATX12V v1.2, which was quite a while ago - ATX12V is now up to v2.2 (PDF). Fortunately, the reason why -5V was removed was that practically nothing needed it any more.


    http://www.dansdata.com/quickshot030.htm

    So its useless...
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