Should my -12v be giving less than 1 volt?

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kitty500cat

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My computer (a Compaq) has a 250 watt Bestec power supply. I think it might be giving some incorrect voltages.

SpeedFan gives the following:

VCORE: 1.58v
+3.3v: 3.31v
+5v: 5.05v
+12v: 11.25v
-12v: 0.72v
-5v: 5.11v
+5VSB: 5.40v
VBAT: 3.25v

I think that I've seen the VCORE at 1.6 volts already; I'm not sure what it's supposed to be. I think the -12v has fluctuated between 0.8v and 0.64v or lower. The low voltage of the -12v has me concerned; maybe it's being reported incorrectly or something. I usually keep my case fan at 100%; but the RPM fluctuates depending on how high the -12v is. When that voltage is lower, the RPM is lower as well.

Should I be replacing my PSU? It is a Bestec, after all; but I've had this computer since September of '05, with no power-related problems yet.
 
As you probably know, Bestec is not one of the better brands. Often used in eMachines, with a decent rate of failure. That does not mean they all fail.

I suggest using a few different programs to measure temp, like: EVEREST or PC Wizard. Compare them with SpeedFan and see if they all show the same. Not all systems have a -12. Can't help you with that.
 
ATX standard says that -12V has to be there! Maybe you mean -5V that was removed from the specification at ATX version 1.2? Of course, whether the actual motherboard makes use of this voltage or whether it has sensors or it, is a completely different matter.

AFAIK the voltage tolerances are 5%, so your +12V and +5V are off limits too.
 
I think that PC Wizard was maybe a few hundredths of a volt off on one or two of the lines, but nothing at all significant. I can't run Everest because I'm a part of a domain.

Should I get a new PSU? Or would more info be helpful?
 
Hi kitty500cat.

Those Bestec psu`s are absolute crap, I wouldn`t have one anywhere near my system. If I were you I`d seriously consider getting a better psu, before the Bestec fails and takes out some of your precious components.

Psu`s by Antec/FSP/Enermax etc are all good brands.

Regards Howard :)
 
OK, thanks guys, I'll look into a new PSU.

I'm looking at this. I like the fact that the efficiency is >80%. Is this a good/bad choice?
 
Those FSP PSU's are excellent. I have a 400W ATX400-PA one, and it works excellent. They're highly recommended :)
 
Sorry, but I just gotta comment....

-12V will definately give you less than 1 volt. Its negative :D
 
OK, cool. I'm a noob at PSUs :D

I think I'll get that one that TangoTrolly mentioned. Thanks, guys!

Regards :)

Edit: hey, it's ordered. I'll let you know how installing goes; I might need some help with that :blush:
 
Update: installed it (the one TangoTrolly mentioned), works fine!

Voltages don't really seem to be much, if any, better; but hey, I got that Bestec out of there.

VCORE: 1.58v
+3.3V: 3.33v
+5V: 4.92v
+12V: 10.88v
-12V: 0.64v
-5V: 5.11v
+5VSB: 5.46v
VBAT: 3.26v
–all according to SpeedFan

Thanks for all your help, guys; I'll let you know if I have any more problems.

Regards :)
 
What motherboard do you have? Maybe the mobo maker (or even HP) has some PC health utility that is able to read your motherboard sensors properly?
 
I Have the Concept, But Not The Color Code.....

CMH said:
Sorry, but I just gotta comment....

-12V will definately give you less than 1 volt. Its negative :D
Click to expand...

Sometimes I wonder if we don't rely too much on programs to do the grunt work.
Any voltage on the power supply could be measured with a digital voltmeter, under load even. Since (generally)there are many extra output wires on the supply, all that needs to be done is to attach the (Red) + lead on the meter to whichever voltage you'd like to measure, while grounding the (black) - lead to the case. This isn't as radical or dangerous as it sound. To measure negative voltage either select the scale for - DC volts or (my favorite) ground the positive red meter lead and use the black to attach to the wire, and negative voltage will read as positive.
What color is - 12 volts? No matter, old brain cells I'd probably forget tomorrow.

I understand that you can't measure Vcore this way.
 
Vcore is the CPU voltage (I think), so you can't really measure that.

My motherboard is an ASUS, so I downloaded Asus Probe. It tells me the following:

+12V: 11.52v
+5V: 4.945v
+3.3V: 3.328v
VCORE: 1.534v

So that's within bounds. Maybe I'll try using my multimeter to physically test the 12v and 5v lines.

Regards :)
 
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