Motherboard voltages look wacky

BobNutfield · 04-28-2006, 02:07 PM

Hi Everyone,

Just a question about what appears to be whacky things going on with my computer. A little while ago the CPU seemed to be getting hot and the activity monitor showed 100% usage (AMD64 3400+). I shut down and let it cool off and things with the temp seems ok now the the cover open and running. However, not being an electrician, I don't understand the voltage readings from lm_sensors. Should I be concerned? is something amiss?

Any help appreciated.

Bob

Code:

it8712-isa-0290
Adapter: ISA adapter
VCore 1:   +1.33 V  (min =  +1.42 V, max =  +1.57 V)   ALARM
VCore 2:   +2.54 V  (min =  +2.40 V, max =  +2.61 V)
+3.3V:     +6.72 V  (min =  +3.14 V, max =  +3.46 V)   ALARM
+5V:       +4.14 V  (min =  +4.76 V, max =  +5.24 V)   ALARM
+12V:     +12.35 V  (min = +11.39 V, max = +12.61 V)
-12V:     -18.28 V  (min = -12.63 V, max = -11.41 V)   ALARM
-5V:       -3.80 V  (min =  -5.26 V, max =  -4.77 V)   ALARM
Stdby:     +4.84 V  (min =  +4.76 V, max =  +5.24 V)   ALARM
VBat:      +4.08 V
fan1:     3245 RPM  (min =    0 RPM, div = 8)
fan2:        0 RPM  (min = 3013 RPM, div = 8)          ALARM
fan3:        0 RPM  (min = 3013 RPM, div = 8)          ALARM
M/B Temp:    +25°C  (low  =   +15°C, high =   +40°C)   sensor = thermistor
CPU Temp:    +22°C  (low  =   +15°C, high =   +45°C)   sensor = thermistor
Temp3:       -11°C  (low  =   +15°C, high =   +45°C)   sensor = diode

puntjuh · 04-28-2006, 02:26 PM

From what i remember from my courses of electric class the PSU voltages are allowed to go 10% up or down the standard amount of voltage.

So for example the +5v is not allowed to go higher then 5,5 and not lower then 4,5.

BobNutfield · 04-28-2006, 02:35 PM

Thank you for that response....if that is so, I may have something going haywire on my board because some of the voltages are way out of that range, but not constantly. Subsequent readings they are in range, then they are out again.

Would like to get the facts if I have something to worry about.

Thanks

Bob

puntjuh · 04-28-2006, 02:48 PM

well .. if i were you i'd check in the bios. The voltages are given there as well.. If it really does continue, i'd consider buying a new Power Supply Unit (PSU), if you don't.. it could (will) kill you're mainboard.

i looked it up on the internet.. and to make it a fact.. here's the link :

http://www.hardwareanalysis.com/content/article/1482.3/

BobNutfield · 04-28-2006, 03:38 PM

Thank you for providing that link. The CPU is running a little hotter that it normally does. Could be voltage related. I shut down and checked in the bios, and the bios is showing simply OK for voltage (Award Bios). It doesn't provide voltage amounts, just says OK. The CPU temp is running about 45C, which I am told is normal, but it usually runs at 36-40C. lm_senosrs is showing it at 27C. I am wondering if lm_sensors is reading it wrong. I am sure there is a way I can check whether lm_sensors is configured to properly read the bios information, which it apparently isn't.

Still, I will take you advice and replace the PSU this weekend. They are certainly cheaper than new mother boards.

Thanks for your help

Bob

BobNutfield · 04-28-2006, 03:44 PM

Another reading from 30 seconds ago...something definitely looks odd. If anyone knows how to check whether lm_sensors is reporting the correct information, I would very much appreciate it.

Bob

Quote:

it8712-isa-0290
Adapter: ISA adapter
VCore 1: +1.33 V (min = +1.42 V, max = +1.57 V) ALARM
VCore 2: +2.56 V (min = +2.40 V, max = +2.61 V)
+3.3V: +6.72 V (min = +3.14 V, max = +3.46 V) ALARM
+5V: +2.63 V (min = +4.76 V, max = +5.24 V) ALARM
+12V: +12.35 V (min = +11.39 V, max = +12.61 V)
-12V: -5.15 V (min = -12.63 V, max = -11.41 V) ALARM
-5V: -2.42 V (min = -5.26 V, max = -4.77 V) ALARM
Stdby: +3.52 V (min = +4.76 V, max = +5.24 V) ALARM
VBat: +4.08 V
fan1: 3183 RPM (min = 0 RPM, div = 8)
fan2: 0 RPM (min = 3013 RPM, div = 8) ALARM
fan3: 2860 RPM (min = 3013 RPM, div = 8) ALARM
M/B Temp: +25°C (low = +15°C, high = +40°C) sensor = thermistor
CPU Temp: +27°C (low = +15°C, high = +45°C) sensor = thermistor
Temp3: -8°C (low = +15°C, high = +45°C) sensor = diode

puntjuh · 04-28-2006, 03:56 PM

perhaps there is usefull information on the lm_sensor site.. here's the link

.

http://secure.netroedge.com/~lm78/index.html

BobNutfield · 04-28-2006, 04:15 PM

Thank you...you have been very helpful.

Bob

weibullguy · 04-28-2006, 04:33 PM

Speaking purely as an electrical engineer and not as an expert on PC hardware...

I would check the voltages at testpoints on the mobo. However, you may not be comfortable poking around with test probes. A go/no-go check might be your fans. When they're reported at 0 RPM, are they? Also, the 5V or 12V is probably being used to power the LEDs (power, HDD activity, etc.). They may dim, seem brighter than usual, or flicker. The 12V is definitely used to spin the fans. The +3.3V is the bias voltage for the vast majority of the IC "chips". At 6.72V, I would expect that several of the components on the mobo would have released their encapsulated smoke by now.

The tolerance of voltages depends on the technology used to manufacture the integrated circuits. Transistor transistor logic (TTL) can usually tolerate +/-10%. Complementary metal oxide semiconductor (CMOS) logic and its derivatives usually require tighter tolerances of 5% or less. It's easier on us dumb engineers to just spec everything at 5% or less rather than trying to remember what's what.

Electro · 04-28-2006, 05:41 PM

The power supply should cost more than 100 US dollars or 79.1510 euros (as of 4/28/2006). I have a power supply from Seasonic model S12-430 (430 watts) provides tighter voltage regulation than 5%. It has active power factor controlled and unverisal voltage that adjusts the voltage by itself.

You will have to adjust it8712 in lm_sensor config file to show correct readings that your BIOS shows.

puntjuh · 04-28-2006, 06:05 PM

I wouldn't use software to check my voltage things. I trust the bios.. software won't be as specific as the bios.

Emerson · 04-28-2006, 06:12 PM

Quote:

Originally Posted by puntjuh

I trust the bios.. software won't be as specific as the bios.

You better don't. Why you think BIOS gets it correct? Simple multimeter will tell the truth. You can use it on main connector, no need to use those clumsy probes on chips.

puntjuh · 04-28-2006, 06:15 PM

I check my bios first. if it says it's ok.. and something is wrong.. then i go use my volt meter (don't know a good translation for it from dutch) on my PSU.

BobNutfield · 04-28-2006, 06:26 PM

Thanks to everyone who responded. Not being an electrical expert, I know surface information that I read. As Arow pointed out, if the readings I was getting from lm-sensors were correct, my motherboard would already be toast. And, as punjuh has stated, the bios is programmed to read directly from the source. Unfortunately, the bios does not give voltage amounts; it simply state that the Vcore voltages are "OK". I have gone through the configuration file in etc/sensors, but I think I would need Arow's EE degree to understand it enough to actually correctly edit it.

I have added one more fan. I now have three auxillary fans, the CPU fan, the fan on the graphics card and the northbridge fan. It's noisy, but cool inside the case. Just to play it safe, I think I will replace the PSU this weekend. The one I have currently is a 550 watt unit I purchased for £25.00 (about $40.00) at a computer fair. I have an nForce2 board (Gigabyte), nVidia 5700FX card, AMD64 3400+, 2 SATA drives, DVD+RW and a CD+RW/DVD. I suppose with all that I should have a quality PSU. For now, everything runs as normal. No problems are obvious. I just didn't want to smell wires burning without warning.

Thanks to everyone,

Bob

BobNutfield · 04-28-2006, 06:54 PM

Did some editing in the etc/sensors file and commented/uncommented two entries regarding the it8712 as suggested by Electro. The sensors now look like this:

Code:

it8712-isa-0290
Adapter: ISA adapter
VCore 1:   +1.33 V  (min =  +1.42 V, max =  +1.57 V)   ALARM
VCore 2:   +2.54 V  (min =  +2.40 V, max =  +2.61 V)
+3.3V:     +3.36 V  (min =  +1.57 V, max =  +1.73 V)   ALARM
+5V:       +3.63 V  (min =  +4.76 V, max =  +5.24 V)   ALARM
+12V:     +12.35 V  (min = +11.39 V, max = +12.61 V)
-12V:      -5.39 V  (min = -12.63 V, max = -11.41 V)   ALARM
-5V:       -5.19 V  (min =  -5.26 V, max =  -4.77 V)   ALARM
Stdby:     +4.35 V  (min =  +4.76 V, max =  +5.24 V)   ALARM
VBat:      +4.08 V
fan1:     3183 RPM  (min =    0 RPM, div = 8)
fan2:        0 RPM  (min = 3013 RPM, div = 8)          ALARM
fan3:     2860 RPM  (min = 3013 RPM, div = 8)          ALARM
M/B Temp:    +25°C  (low  =   +15°C, high =   +40°C)   sensor = thermistor
CPU Temp:    +27°C  (low  =   +15°C, high =   +45°C)   sensor = thermistor
Temp3:        -7°C  (low  =   +15°C, high =   +45°C)   sensor = diode
vid:       +0.00 V

A little closer to what they are supposed to be, but still a little wacky. Have no idea what "vid" is, but the instructions said to comment it out with this chip. It also said that with the chip, if the 3.3v readings were 2X normal, to uncomment a variant formula, which I did. This was the result.

Hopefully, this information may help someone else with similar questions.

Thanks,

Bob