Tech Support > Computers & Technology > Negative voltages
Negative voltages
Posted by Gilligan Monger on July 14th, 2003


I've recently built a new Pentium 4 system and have hooked it up to
Motherboard Monitor just to keep an eye on the temps, fans and voltages
whilst it burns in. I notice MBM defaults to displaying your -5v and -12v
lines, and displays mine as running at c. -2.8v and -8.2v. My question is,
are these rails used for anything anymore, and if so why are mine showing
such big variances? Indeed, in what situation does any device require a
negative voltage?

Last question - I know it's possible to monitor your Vcore voltge and Core
1, which is currently reading my memory voltage supply, but does anyone know
of a way to monitor the AGP voltage. I using an Abit IC7 for what it's
worth.

Cheers


Posted by Ed Light on July 14th, 2003


Somone with more knowledge will probably answer, but in the meantime, I
think MBM makes a guess at each display, and you can go into the settings
and hunt for the proper sensor that matches.

I have one fan it can't display properly at all.

Can't go look at it as I'm booted to a clean install I haven't built up yet.

--
Ed Light

Smiley :-/
MS Smiley :-\


Posted by Strontium on July 14th, 2003


Use the program, that came with the motherboard. MBM is not, yet, up to
par with P4 motherboards. I used MBM, for years, with AMD based boards.
They need time to figure out the new P4 boards.

-
Gilligan Monger stood up, at show-n-tell, and said:

--
Strontium

"Shortcuts are self-defeating. Mean. If you cannot do it,
clean, you'll never reach your reward..." - 311




Posted by Alien Zord on July 14th, 2003


"Gilligan Monger" <gillig@n.net> wrote in message
news:3f123a9f$0$23587$5a62ac22@freenews.iinet.net. au...
MBM (and Speedfan) frequently misinterpret voltage and temp readings.
Check in the BIOS and compare.
AFAIK -5V is not used by any device, -12V is used by the serial ports
only and as far as they are concerned anything between -5 and -15V will
do.
I don't know of any mobo that monitors the AGP supply line. With all the
oveclocking and overrunning maybe its time the mobo makers considered
it.



Posted by jaster on July 14th, 2003



"Gilligan Monger" <gillig@n.net> wrote in message
news:3f123a9f$0$23587$5a62ac22@freenews.iinet.net. au...
THG articles. There's a link off MBM5 to take you to the MBM5 forum
website. MBM's author Alex Van Kaam should be able to answer your questions
about voltages.



Posted by Pen on July 14th, 2003


In the latest specs the -5 is optional, while the -12 is usually used
just for serial ports. However, some analog sound uses +/- 12.

"jaster" <jaster@home.still> wrote in message
news:rJyQa.601$kK6.84@newssvr22.news.prodigy.com.. .

Posted by Pen on July 14th, 2003


To clarify RS232 is a bipolar signal. From the specs.

Signal State Voltage Assignments - Voltages of -3v to -25v
with respect to signal ground (pin 7) are considered logic '1'
(the marking condition), whereas voltages of +3v to +25v
are considered logic '0' (the spacing condition). The range
of voltages between -3v and +3v is considered a transition
region for which a signal state is not assigned.

As you can see it requires both + and - voltages. Normally
in PCs +/- 12 volts is used.


"jaster" <jaster@home.still> wrote in message
news:QDCQa.683$ba.38@newssvr22.news.prodigy.com...


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