I have MbProbe which is just like MBM the question I have is due to my -5V ... It is reading from -5.66 to -5.81V ... is this normal for AMD, or is there another problem I am not aware of??? And please forgive me if this is in the wrong section of the forum.

Any idea what the -5v rail is used for??

Intel eliminated guidance for the -5v rail with ATX12V v1.3 PSU spec (2003). In other words, don't worry about it.

Intel eliminated guidance for the -5v rail with ATX12V v1.3 PSU spec (2003). In other words, don't worry about it.

That's cool to know, but if you looked at my system it's an AMD Duron 750mhz (spitfire). made before 2003. Although I am no computer guru and the power supply was made in 1999. That is why I said "should I be concerned about it" especially since I have fried 2 PSU's in this system.

If you fried two PSUs on an old Duron system, you must be buying garbage units. Either that or you're overloading the hell out of them. You could easily get by with a decent 250W PSU unless you have numerous HDDs & a high end video card that requires the PSU plug-in.

The older ATX spec states that the tolerance for the -5v rail is 10% +/-, so anything between -4.5v & -5.5v is considered OK. Regardless, the -5v rail hasn't been used for years. Since you seem to think it's important, can you tell me what it's used for??

What you should concern yourself with are the "big three"...+3.3v, +5v & +12v. Of them, the +12v is most important. On an old system like your's, you should be able to get by with a minimum of 15A on the +12v rail unless you're overloaded with +12v devices (HDDs, optical drives, floppy, fans, etc).

http://www.dansdata.com/psus.htm

One last point is that you're relying on a software program for your voltages. Did you checked the BIOS to see if they're being reported the same? Have you tried a voltmeter? If you think the -5v rail is responsible for bringing down your PSUs, you're "barking up the wrong tree".

As to your question is if I know what the -5V is used for that would have to be a "no" ,but I'm sure I can Google it up. As for my system itself it has

1 PCI 4meg video card
1 AGP 4x 64meg Abit Siluro 400-which has a Nvidia GeForce2 MX400 chipset, which has been overclocked which does not plug into the PSU.

2 5400rpm Ata 100 hard drives
2 CD/RW drives
1 3.5" Floppy
2 120mm Fans
1 80mm Fan
Network card is built on the mobo

And BIOS does give the same Voltages as MbProbe.

As you posted a 10% tolerence for -5V between 4.5V to 5.5V is fine .... mine is past that point from -5.6V to 5.8V.

I'll have a look on Google and see what the -5V rail is for.