low -5v issue

[MWTungsten]

I've just built a new PC with an Enermax Noisetaker 485W and Soltek SL-K890Pro. Soltek's monitoring software is showing good strong (green) voltages in everything except "-5v" (note: not +5v, that is high) which is red at "-3.894". I'm not sure if I should worry about this?

 

[lenjack]

Forget it...modern computers don't use the -5v line. In fact some power supplies don't even provide one.

 

[Leros]

Some (most modern) floppy disk drives use 5v.
USB devices are 5v.
Some old processor are 5v.
Im sure many other important things are 5v.

"For most AMD processors, the 5V supply must provide at least 18A. For the new Intel P4 processors, the 5V must provide at least 20 amperes. Both AMD and Intel P4 also require the +5V standby can provide at least 720mA or more. Without suffcient 5V and 12V current from the power supply, the system may become unstable/unreliable and may experience difficulty to power up the system."
Text

 

[MWTungsten]

So what is the significance of (for example) +5v vs -5v?
I'm embarrased to admit I don't know what these #s mean.

 

[lenjack]

JToxic... many items in a modern computer use plus 5, but nothing in the computer uses minus 5.

 

[Zepper]

The -5V line has been totally deleted from the ATX spec as of the last rev. It has been optonal since ATX 2.0. As others have said above, nothing uses the -5V line any more so fageddaboudit...
. Switching regulators have a problem regulating without a load (nothing uses = no load) - so if you want that to show an accurate reading, tack a 100 Ohm resistor between the -5V line and ground.
. The polarity of Voltage is expressed relative to Ground (0 V) so +5V means 5 volts above Ground and -5V means 5 volts below ground. If you connect the +5 to one end of a resistor and the -5 line to the other end, then you have 10 Volts across the resistor.


.bh.