Help! CPU fan finnicky...motherboard?

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trogdor

trogdor

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Well this may be more of a PC question than recording...

I built my first PC about a month ago, Athlon 2100+, Abit NF-7, etc...

Everything has gone smoothly so far until today when i tried to play an audio CD...turns out I had accidentally plugged the Analog Audio Output cable from the CD-ROM upside down into the motherboard...this resulted in a high-pitched whine, and all sounds coming out in a "slow-motion" sound. I rebooted and went into bios to find the CPU temp just over 60 degrees celsius... needless to say I nearly crapped my pants and practically ripped the plug out of the wall.

After finding the problem and flipping the analog audio plug on the motherboard, I was still getting some extra heat and found out that the CPU fan wasn't running... I turned the computer off and then on and the fan would spin full speed for about 3-5 seconds and then just stop.

Is it possible that by having the analog audio cable upside down i inadvertantly sent voltage on the motherboard where no voltage should go, causing damage?

Everything else seems to be fine...after turning it off and on a few times the CPU fan came on and stayed on...but i'm still concerned that something might be wacky. Until I get it figured out i'm running motherboard monitor and watching my heat like a hawk...

thanks in advance for any suggestions,

trogdor
 
Trogdor, CPU fans are often the cause of overheating. Some just go slow and some makes lose their "tightness" quickly and the resulting slackness causes poor heat transfer. I have noticed that more recent fans have copper transmission pads which transfer heat better. If you are ever tempted to remove the CPU fan then it is really better to replace it with another, due to it then losing its "grip". Also I have noticed that the bios upgrade on my motherboard (Asus) in the latest issue corrected an error in reporting the CPU temperature in the Motherboard monitor bit of the bios. So that may be worth looking at. Don't forget to smear that white silicon thermal paste between the CPU and the fan. With regard to the audio cable I wouldnt have thought that reversing this would send any adverse voltages thro to your mobo. In fact the "slow motion" sound you describe sounds more like a CD/DVD drive fault to me than a cable problem.
 
trogdor said:
I rebooted and went into bios to find the CPU temp just over 60 degrees celsius... needless to say I nearly crapped my pants and practically ripped the plug out of the wall.
Click to expand...
60 and a bit won't hurt the cpu by the way. 75-80 is roughly the upper limit.
 
thanks for the replies you guys... i'll try updating the bios on the motherboard, though it is new. Maybe they have more recent ones on the abit website.

I understand what the cpu fan does...my problem is that the fan will either spin for a couple seconds when i turn on the computer and then stop, or will work while i use the computer and then stop maybe twenty minutes into use, causing the cpu heat to rise. although it's not reaching dangerous temps yet, the cpu fan has always run constantly...also, once it has stopped, it doesn't come back on...even as the cpu temp rises... without turning off and on the computer. So i'm thinking that this is probably a motherboard fan sensor issue or something. Like I said, I'll try updating the bios. If that doesn't work, are there ways around plugging the cpu fan directly into the motherboard? such as a fan that just plugs straight to the power supply?

My mobo wasn't recognizing the LAN cable this morning either which makes me think i may have done something to the motheboard itself.

#$@#$! computer problems...too many possible solutions!!

any help is appreciated, thanks

trogdor
 
If the fan is slowing down it MUST be replaced first since this is the cheapest part. I wouldnt operate the computer until you have done that first. If its a PS or Mobo problem that will then be more obvious after that! I would then closely monitor the replacement fan after that with the case off. Sorry if I sounded patronizing about your fan's function!!:)
 
AMD specifies that their processors can withstand temperatures up to 90 C. The problem is that the motherboard can't alway stand these temperatures. Unles you have parts on hand to test with, you're basically shooting in the dark. It seems to me that the fan is OK, but the motherboard is shutting it off. Other than that, I'm afraid your about to get into the "change it and see if it works" game.
 
yea i'm pretty sure that the fan is still fine...

and my cpu temp usually idles around 33-34 when it's running...I think it's a motherboard thing. Gonna try updating bios and cross my fingers.

thanks guys
 
Okay well I've been monitoring the fan speed, and found a pattern.

The CPU fan runs typically around 2800rpm when i turn the computer on...but gradually slows down over the course of usually about 15-20 minutes. Once it reaches 2500rpms the fan just stops.

I unplugged the CPU fan from the motherboard's "CPUfan" plug, and tried it in the mobo plug for "CASEfan". It did the same thing...slowing gradually ovder about 20minutes and then stopping.

Does this sound like a problem with the cpu fan to you guys?

I might try to get a 3pin to 4pin adaptor so I can plug the cpu fan directly to the power source... the only thing is that I won't be able to monitor its speed hooked up that way.
 
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