Voltage oddeties

Lt_Dan · Post by **Lt_Dan** » Fri Oct 02, 2009 1:30 am

Hey,
I've got a weird problem\question.
when i check the Voltage in speedfan, it says as follows:

how come my -12v rail gives out -16.97v?

thanks a lot,
Dan.

Mr Evil · Post by **Mr Evil** » Fri Oct 02, 2009 3:20 am

Don't worry about it. Most motherboards seem to be unable to read -12V correctly, or at least SpeedFan fails to. Almost nothing even uses that voltage anymore.

Lt_Dan · Post by **Lt_Dan** » Fri Oct 02, 2009 3:37 am

what is it used for?

what program can i use to read it properly?

is it something to do with connecting 3 fans to each fan header on the mobo?

lm · Post by lm » Fri Oct 02, 2009 4:35 am

EDIT: removed misinformation, sorry.

Lt_Dan · Post by **Lt_Dan** » Fri Oct 02, 2009 6:01 am

what's isa slots?

worrying is the source of a lot of problems! but you can't help but worry from things you don't understand..

i don't to cause any damage to the system.

Mr Evil · Post by **Mr Evil** » Fri Oct 02, 2009 7:15 am

Lt_Dan wrote:what is it used for?..

I recall hearing that older sound cards used it. I tried googling to check, but Google ignores the "-" symbol, even if I use quotes

.

Lt_Dan wrote:...what program can i use to read it properly?..

SiSoft Sandra is pretty good. You might not be able to read it at all though, if the motherboard hasn't implemented the hardware necessary to do so.

Lt_Dan wrote:what's isa slots?...

ISA was the predecessor to PCI.

lm · Post by lm » Sun Oct 04, 2009 3:36 pm

I have to correct a mistake I made earlier: seems -12V is still in use, -5V was the thing that was used by ISA slots and which is no longer present on PSUs today. However the other points still stand, most likely the software just can't give correct numbers or the hardware doesn't really measure that voltage.

The link below says that normally at most 0.3A would be drawn from -12V line, no matter how much load is elsewhere, which would mean a load of less than 4W or at most 1% of the total load is on that line for a 400W total load which was one of the examples provided in the document.

So -12V is probably completely irrelevant relic just like -5V was?

http://www.formfactors.org/developer%5C ... ev_1_1.pdf