PSU no -5 volt rail, question

My brother owns a Pentium III computer. His power supply died and he purchased a 460 watt switching power supply [from Qtechnology, 460 watt, model number QT-03460G]. He called me and asked if I would install it, which I did. After installing it, I booted into BIOS and checked voltage.

He has a Pentium III computer.

The BIOS reported a problem with -5 volts [it was reading -12 volts]. I checked the cable to the motherboard and found that there was no wire and pin for -5 volts coming from the PS.

We found no written material in the box that the PS came in, the outside of the box listed voltages for the PS, -12 volts was listed but -5 volts was not.

A computer uses 1s and 0s to comunicate data, greater than +3 volts means 0, less than -3 volts means 1, close to 0 volts means no data is being transmitted.

So, are newer motherboards/power supplys only using -12 volts? Will using a PS with only the -12 volt line work in a Pentium III mainboard?

Thank You,



Apr 27, 2005
So you say it's a Pentium III? It sounds like that PSU is rated for a P4, which is plenty for a P3. I seriously doubt that there would be any difference PSU-wise, because P3's would be blowing up all over the place.

<b><font color=blue>Athlon64 3200+ Winchester/MSI Neo4 Platinum SLI/MSI 6800 Ultra/1 GB Kingston HyperX (Dual Channel)/74GB WD Raptor/600Watt Enermax Noisetaker/ Dual Mitsubishi 21 Inch Monitors</b></font color=blue>


Former Staff
Set BIOS to ignore the -5v reading as I doubt any hardware is using it.

<font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
<font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>