NO -5 volt on Psu

applewoodgo

I have just tested the PSU in a Dell Desktop with a Dr Power PSU tester and discovered that the -5 Volt is dead, ie., the -5 Volt LED doesn't light. What is this controlling on the computer and what should the effect of this failure be?

Torqay

applewoodgo wrote: »

What is this controlling on the computer and what should the effect of this failure be?

PCI cards, hard drive circuit boards, USB ports rely on 5V... to name but a few.

Get on to Dell and order a replacement (though few models can use generic PSUs it's safer to get one from Dell).

applewoodgo

Torqay wrote: »

PCI cards, hard drive circuit boards, USB ports rely on 5V... to name but a few.

Get on to Dell and order a replacement (though few models can use generic PSUs it's safer to get one from Dell).

Thanks for the post. Just to clarify, I have a +5 Volt led lighting on the tester; the -5 Volt is not lit. All led's are lighting bar the -5 Volt.

Redisle

I don't think negative voltages are so important on PC PSU's anymore. They were used in the past for voltage levels on serial ports as suggested here.

Generally used to provide a large differential voltage for some component.

The ATX 24 standard does not have a -5V pin regardless so I'm not sure why a PSU tester would even have an indicator for one tbh.

Modern PSUs do not have the -5V rail, it was only used for some old ISA cards.

applewoodgo

Redisle wrote: »

I don't think negative voltages are so important on PC PSU's anymore. They were used in the past for voltage levels on serial ports as suggested here.

Generally used to provide a large differential voltage for some component.

The ATX 24 standard does not have a -5V pin regardless so I'm not sure why a PSU tester would even have an indicator for one tbh.

Many thanks; question clarified.