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High motherboard temperature /  High -5V voltage sensor reading.

Posted on 2003-10-26
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Last Modified: 2013-11-10
I recently had problems with spontaneous shutdowns of my machine, and i ignored it at first.  I then found out that two of my three cooling fans were not working.  I imeadiately replaced them and they now work fine.  In the process, I downloaded SiSoftware's Sandra monitering program to monitor the temps of the machine.  Replacing the fans turned off the warning for high CPU temp and high powersource temp, yet it is still giving me a high mainboard temperature reading of 65 degrees C.  I also noticed that the -5V voltage sensor reading is up to -8.9V.  I assume these two problems are related, but i have no idea what to do from here.  Any insight?  Im running an HP pavillion 1.8GHz machine.  The motherboard is a KM266-8233.

Its possible that when the fans were broken, I fried a certain component on the motherboard which is causing the voltage to swing low.  Should i worry about it, and if so, what should i do?  

thanks in advance,
David Yaylali
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Question by:DavidYaylali
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16 Comments
 
LVL 18

Expert Comment

by:Wakeup
ID: 9624879
I would worry about it.  It is also possible the Power supply is causing your problems as well.  Overvoltage or undervoltage can cause problems.  I would suggest replacing it.  However being that it is an HP computer, and may possibly be running a proprietary power supply, it may not be easy to replace.  You may try taking your computer to a local Computer store to see if they can acquire a similar power supply or to check and see if it is a proprietary HP Power supply.

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LVL 32

Expert Comment

by:_
ID: 9625047
That is borderline high. What is the CPU temp?
Check that the fans are not blocked ( airflow ), especially the intake fan and grill.
With your hand a couple of inches from the powersupply fan, how hot does it feel?
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LVL 8

Expert Comment

by:SNilsson
ID: 9625136
Also check the Bios readings and compare them with Sandra's, if they are different maybe Sandra is not reading it correctly.
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LVL 18

Expert Comment

by:Wakeup
ID: 9625165
well....coral47, he replaced the fans?  or at least some of them....but it is quite possible he may not have changed some of the crucial fans...like CPU fan or power supply/power supply fan....
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LVL 12

Expert Comment

by:public
ID: 9627201
Feel the motherboard with your fingers. If some parts are too hot you have a problem
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Expert Comment

by:SNilsson
ID: 9628067
... yes second degree burns on the fingers :)
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Author Comment

by:DavidYaylali
ID: 9630852
The fans I replaced were the power source fan and the chasis fan.  The CPU fan seems to be working properly. The only part that seems to be getting real warm is the north bridge (VIA VT8375).  Its pretty hot, but I can touch it without burning myself.  This chip is right next to the CPU, so i think its bumping the CPU temp up a bit. I has a heat sink, but i tried attaching an even bulkier heatsink to it.... no effect...motherboard still reading 66 degrees celcius.  Should i attach a fan to this heat sink?  
coral47:  The air out of the power supply fan is warm, yet it doesnt feel abnormally warm.  (by the way i have no experience with building computers, only basic electronics, so i cant be sure about my use of words like "abnormally")
Wakeup:  your probably right that the problem lies within the powersupply.  Since the fan was broken for a while it probably overheated and fried one of the circuit components.  when i get the chance ill look at it and see if these is something obviosly burnt out.  Maybe i can just replace a transistor or something.  
I am away from my computer now, so ill check on the CPU temp and fan speeds, etc. later on tonight.

Thanks to everyone for the insight!
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LVL 32

Accepted Solution

by:
_ earned 63 total points
ID: 9631557
My rule of thumb for exhaust fan heat: ( PSU )
With your hand about 1/2 inch from your mouth and cupped, and your mouth wide open, exhale through your mouth normally a couple of times while inhaling through your nose. If the fan feels much warmer than that, it needs to be looked into.
I find this to be a quick and easy way to keep tabs on my machine, without having to popup the temp program.

Wakeup: Yeah, new fans. But if a cable is blocking the airflow or the intake holes are dirty/blocked, the cool air won't do much good. I have dropped as much as 10 F just by tieing up cables. < to be fair, I did have 2 IDE Channels, 2 Floppies, and a SCSI CDROM in a Mini tower case, Makes for a lot of ribbon cables in a small space  ; )  >
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LVL 18

Assisted Solution

by:Wakeup
Wakeup earned 62 total points
ID: 9631846
Coral47,  

You dont want to know how many things I have in my machine!  ya sure you do....hehe....
I have 6 hard drives, a SCSI CDrom, DVD rom and CDRW, oh and FDD.  But who'se counting! :)

It may also be a bad motherboard or a bad sensor on the motherboard...I had customer come in with a system that was overheating.  Didn't matter which fan or heatsink or how much thermal grease or etc etc etc, it would report a high temperature.  Swapped out the motherboard and the problem went away.  It also happened to me.  I had a new board and processor, and had a heat issue.  My system would heat up soooo fast and hit over 70 degrees C.  Then replaced the board and everything was fine.

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LVL 32

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by:_
ID: 9639214
Wakeup: >>>how many things I have in my machine<<<  I'm impressed.  6 HD's is nothing to sneeze at.   : )
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LVL 18

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by:Wakeup
ID: 9655825
hehe...I actually used to have 8.  Had two scsi drives as well..but those were piddly 2gig and 4 gig drives....
And I actually have a few spare HDD's lying around...in fact I have two 40 giggers in a dual firewire box I am currently using as well...hehe.  
My other machine has two 120's and a 100.  I also move my dual firewire drives to that every once in a while....

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LVL 32

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by:_
ID: 9661965
Sweet.  : )
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LVL 1

Expert Comment

by:asurada2003
ID: 9719484
Get better coller.
I'm using cooler master liquid cooler.
Now my CPU temp are maintain at 50c.
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by:_
ID: 12245459
Thank you much.    : )
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