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Power Supply Voltages question

Last response: in Components
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February 21, 2004 7:18:17 AM

Hello. I just swapped power supplies from one computer to another (because a second power supply bit the dust). After turning the computer on, my Hardware monitor warned me that my -12V rail was at -14.9. My question is, what is the -12V rail used for, what impact will the -14.9 have on my computer, and would it be wise to get a new power supply? To my understanding from reading posts on this forum and websites, the -12V rail is not used much in today's computers. Will it matter if it exceeds the limits? It might be worth noting that I bought my computer in Malaysia in August 2003 and am currently using it in Canada (Malaysia uses 230V and Canada uses 115V). I have no clue if that was relevant.

PSU: Novia (I am assuming noname) 350W
CPU: AMD Athlon XP 2500+ Barton
Motherboard: Abit NF7-S V2.0 (Onboard sound, LAN, raid)
RAM: 2*512 NoName DDR PC2100 RAM
Storage: Seagate 120gb SATA
Video: Elsa 128mb Radeon 9800 SE
Disk Drives: 1 floppy, 1 DVD-ROM, 1 CD-RW
3 Case Fans

Using Winbond Hardware Doctor that was packaged with my motherboard and recommended by AMD for my hardware.

Thank you very much for your time. Any input would be appreciated.
February 21, 2004 7:26:36 AM

If this reading is correct I would ditch that PSU immediatly.
I my experience, several monitor programs doesn't show the negative voltages correct. Verify your reading with BIOS or other programs.
Ofcourse if the -12V rail isn't used, it can be pretty much anything without problems. However, how do you know? You may end up frying your (onboard) sound card.
Regarding 230/115V. Does the PSU have a switch on the rear you need to change? If the switch is still on '230' and you only feed it 115, it may do some weird things (although I would expect it wouldn't start at all. But hey, you never know).

<i><b>Engineering is the fine art of making what you want from things you can get</b></i>
February 23, 2004 12:07:53 AM

I'd ignore it, I don't know of any devices that use negative logic or whatever they call it any more. It might have been for ISA slots, they would have been around back then. Modern boards don't even have ISA slots.

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