Runaway cooling fan

  • Thread starter Thread starter Mint
  • Start date Start date
M

Mint

A friend has a Optiplex 755 and one of the cooling fans runs
constantly.

System Information for Windows shows normal CPU and hard drive
temperatures.

I ended one process that was using a lot of the CPU, but nothing
changed.

Any other things I can look at?

Thanks.
 
Mint said:
A friend has a Optiplex 755 and one of the cooling fans runs
constantly.

System Information for Windows shows normal CPU and hard drive
temperatures.

I ended one process that was using a lot of the CPU, but nothing
changed.

Any other things I can look at?

Thanks.
Click to expand...

In addition to an air blockage, another reason for a
runaway fan, is a clip breaks on the heatsink, and the
heatsink is no longer being pressed tightly against
the CPU. If the heatsink is dangling, then the CPU
gets really hot. And the fan stays on constantly.

There are two pictures of the Optiplex 755 here
(near the bottom of the page). It's a BTX layout,
with the main fan doing double duty as both a CPU cooler,
and a "whole computer" cooler.

http://en.community.dell.com/support-forums/desktop/f/3514/p/19120948/19243934.aspx

Now, another possibility, is the aluminum heatsink to the.
right of the really big cooler, has fallen off. I thought
the idea was, the BTX motherboard may measure temperature
in more than one "zone", and use the temperature information
to decide what fan speed to run. Check to make sure the
steel wire that holds the aluminum heatsink, is still secure.

Also, if the computer is insane (won't pass POST), the main
fan will remain in high speed mode. The fan would probably
slow down, once Windows is running. So if the fan
runs full speed, and the monitor remains black, it means
the CPU isn't reading any BIOS code from the flash chip.

There are probably a total of three fans involved there.
The main fan on the big cooler, is a monster (> 100 CFM).
It can make a lot of noise, when cranked. The video card
probably has a fan. The power supply should have a fan too.
But in terms of sound effects, the main fan on the CPU,
can make a noise like a vacuum cleaner.

Paul
 
A friend has a Optiplex 755 and one of the cooling fans runs
constantly.

System Information for Windows shows normal CPU and hard drive
temperatures.

I ended one process that was using a lot of the CPU, but nothing
changed.

Any other things I can look at?

Thanks.
Click to expand...

Same as what the others said but get a LARGE can of compressed air and
blast out the exhaust fan in the PSU and not just the heatsink fans. I
think the heatsink doesn't have a fan on it if I remember right, just
a housing and large heatsink. I have 755 SFF at my site and they run
quiet. Never dusted since 2008. If you have an air compressor and
blower attachment, that'll REALLY get out the dust.

- Thee Chicago Wolf [MVP]
 
Paul said:
In addition to an air blockage, another reason for a
runaway fan, is a clip breaks on the heatsink, and the
heatsink is no longer being pressed tightly against
the CPU. If the heatsink is dangling, then the CPU
gets really hot. And the fan stays on constantly.

snip
Click to expand...

Seriously? This scenario is highly unlikely.

First of all, the OP stated the CPU temps were normal. If the heat sink
were no longer secure, no amount of fan speed would cool the CPU, and it
would be overheating or even shutting down.

Secondly, while it's not impossible, it is extremely improbable that the
clip on the heat sink would break of its own accord in service. The
only time I have ever seen those type of clips break is DURING a
replacement or installation procedure on the heat sink, not months or
years after the installation.
 
First of all, the OP stated the CPU temps were normal. If the heat
sink were no longer secure, no amount of fan speed would cool the
CPU, and it would be overheating or even shutting down.

Secondly, while it's not impossible, it is extremely improbable
that the clip on the heat sink would break of its own accord in
service. The only time I have ever seen those type of clips break
is DURING a replacement or installation procedure on the heat
sink, not months or years after the installation.
Click to expand...

I've seen several examples of the clip breaking on their own, years
after manufacture. They were all Dell computers. The clip was a spring-
y metal band that was laid across the fan/heat sink and anchored to
eyehook-like points that were soldered into the motherboard. The
eyehooks came loose from the motherboard and the heat sink fell off.
The CPU overheated immediately and the computer shut down and would not
complete a bootup.

I fashioned new eyehooks out of safety pins, soldered them onto the
motherboard, reattached the clip, and the computers have been working
fine ever since, as far as I know.

I'm sure this is not the problem in this case.
 
Mint

Most unlikely to be the CPU fan since the CPU is running at normal temp. If it was
the CPU fan then your heatsink would be out of whack (not in place correctly). Have
you checked the PS fan which can run constantly if the PS is running hot on account
of heavy dust bunnies and not getting enough cooling. Did you isolate the noise to
the fan yet ??

--
Peter
Please Reply to Newsgroup for the benefit of others
Requests for assistance by email can not and will not be acknowledged.
This posting is provided "AS IS" with no warranties, and confers no rights.
http://www.microsoft.com/protect
 
Nil said:
I've seen several examples of the clip breaking on their own, years
after manufacture. They were all Dell computers. The clip was a
spring-
y metal band that was laid across the fan/heat sink and anchored to
eyehook-like points that were soldered into the motherboard. The
eyehooks came loose from the motherboard and the heat sink fell off.
The CPU overheated immediately and the computer shut down and would
not
complete a bootup.

I fashioned new eyehooks out of safety pins, soldered them onto the
motherboard, reattached the clip, and the computers have been working
fine ever since, as far as I know.

I'm sure this is not the problem in this case.
Click to expand...

We had almost all Dells for years where I worked, and also at two other
sites I supported, and I never saw that. I wonder if it was a
particular model that had the problem. The clips you describe sound
like Socket A or Socket 7 types...were they?

Safety pins! I love it! The people in the local hardware store know
better than to help me anymore. They used to ask what I was looking
for, and I'd start describing what I was trying to do with some oddball
plumbing or electrical part, using it for some unrelated
application...and they'd back away slowly! lol!
 
We had almost all Dells for years where I worked, and also at two
other sites I supported, and I never saw that. I wonder if it was
a particular model that had the problem. The clips you describe
sound like Socket A or Socket 7 types...were they?
Click to expand...

I said "several", but it was really only three or four. It's been a few
years now and I don't remember what socket form they were. They were
all similar models bought around the same time. It was obviously a bad
design decision and presumably Dell eventually fixed it.
Safety pins! I love it! The people in the local hardware store
know better than to help me anymore. They used to ask what I was
looking for, and I'd start describing what I was trying to do with
some oddball plumbing or electrical part, using it for some
unrelated application...and they'd back away slowly! lol!
Click to expand...

The first one I had, the little eyelet seemed to have been lost when
the clip sprang open. I cut off the ends of a small safety pin and used
the loop end as a new eyelet and soldered the two short pins back into
the original two holes in the motherboard. I later found the original
eyelet wedged into a corner of the case, but my handmade fix seemed
sturdier than the original, so when the others showed up with the same
problem, I used my trick on them, too.
 
glee said:
We had almost all Dells for years where I worked, and also at two other
sites I supported, and I never saw that. I wonder if it was a particular
model that had the problem. The clips you describe sound like Socket A or
Socket 7 types...were they?

Safety pins! I love it! The people in the local hardware store know
better than to help me anymore. They used to ask what I was looking for,
and I'd start describing what I was trying to do with some oddball
plumbing or electrical part, using it for some unrelated application...and
they'd back away slowly! lol!
--
Glen Ventura
MS MVP Oct. 2002 - Sept. 2009
CompTIA A+
http://dts-l.net/
Click to expand...

When I read Nil's post, I knew it sounded familiar. It was the chipset
heatsink clip that would come loose, shut the PC down, and keep it from
booting up again.
Here's a picture of the offending part:
http://media.hardwareanalysis.com/articles/large/10302.jpg

and two articles about it:
http://www.computing.net/answers/hardware/my-chipset-heatsink-fell-off/28145.html
http://www.computing.net/answers/hardware/chipset-heat-sink-solderdown-ancho/29093.html

Seems the retaining clip is part of the detection circuit, and shuts it down
when the circuit (clip) is broken.
 
When I read Nil's post, I knew it sounded familiar. It was the chipset
heatsink clip that would come loose, shut the PC down, and keep it from
booting up again.
Here's a picture of the offending part:http://media.hardwareanalysis.com/articles/large/10302.jpg

and two articles about it:http://www.computing.net/answers/ha.../answers/hardware/chipset-heat-sink-solderdow...

Seems the retaining clip is part of the detection circuit, and shuts it down
when the circuit (clip) is broken.
Click to expand...

The computer is at a senior center, so popping open the case probably
won't be an option.

There are 3 other exact models and none of them are doing it.

I am thinking.

Bad sensor or bad fan ?

Seems like I saw a program once that could control the fan speed.
It supported a lot of motherboards.

I'll look around.

Andy
 
Mint said:
The computer is at a senior center, so popping open the case probably
won't be an option.

There are 3 other exact models and none of them are doing it.

I am thinking.

Bad sensor or bad fan ?

Seems like I saw a program once that could control the fan speed.
It supported a lot of motherboards.

I'll look around.

Andy
Click to expand...

If you try to slow down the fan without finding out what the problem is, you
may run into even more problems than a loud fan. I would let your friend
know that you have to have access to the innards of the PC in order to fix
it properly. It could be something as simple as the plug has come slightly
loose, not making a connection on the sensor leg, and forcing it to run
fast. Or, as others have pointed out, it could be dust blocking the
circulation around and through the CPU heatsink, and by forcing the fan to
run slower, you'll be overheating the CPU. Sort of a "damned if you do,
damned if you don't" scenario.

I don't think my earlier post has anything to do with your problem; it was
just a follow-up to Nil's post of the heatsink clip breaking.
 
When I read Nil's post, I knew it sounded familiar. It was the
chipset heatsink clip that would come loose, shut the PC down, and
keep it from booting up again.
Here's a picture of the offending part:
http://media.hardwareanalysis.com/articles/large/10302.jpg

and two articles about it:
http://www.computing.net/answers/hardware/my-chipset-heatsink-fell-off/28145.html
http://www.computing.net/answers/hardware/chipset-heat-sink-solderdown-ancho/29093.html

Seems the retaining clip is part of the detection circuit, and
shuts it down when the circuit (clip) is broken.
Click to expand...

Yes, now that you remind me, I believe it was the chipset heat sink,
not the CPU. Our clip looked a little different that the one in that
picture, but the anchor loops on the motherboard look just right.

Ah, the good old days when we'd keep our computers going with baling
wire and chewing gum.
 
glee said:
We had almost all Dells for years where I worked, and also at two other
sites I supported, and I never saw that. I wonder if it was a
particular model that had the problem. The clips you describe sound
like Socket A or Socket 7 types...were they?

Safety pins! I love it! The people in the local hardware store know
better than to help me anymore. They used to ask what I was looking
for, and I'd start describing what I was trying to do with some oddball
plumbing or electrical part, using it for some unrelated
application...and they'd back away slowly! lol!
Click to expand...

Actually, certain models of cooling devices, are notorious for
failing. And for good reasons.

On some AMD systems, the socket has three plastic tabs for the clip
to snap onto. And some genius heatsink designers, fit a "one-hole"
clip onto the plastic. And then apply extreme pressure on the clip.
After a couple years, the single plastic tab, snaps from the abuse.

There have also been cases, of some of the Intel plastic ones snapping.
So it is possible for cooler parts to fail while in use, and
without mechanical shock being the reason for the failure. All
it takes, is plastic... and stress.

My current after-market cooler, uses screws and nuts. And I can
be reasonably assured it won't fall off.

The Northbridge cooler, is sometimes held in place with a
spring steel wire. And it hooks onto some U-shaped things
soldered to the motherboard. Due to the metal chosen for the
U-shaped thing, it doesn't solder well. (I have one design
here, that uses stainless steel for the hook, when a tin-lead
interface should have been used. They can pull out of the motherboard,
because of the lousy solder joint.) You can see an example
of a U-shaped thing, pulled out here.

http://sequimpc.com/images/IMG_1940.jpg

Paul
 
Look did you clean the dust around the Processor First.
if it did not work we
be reed to move on to the Sec. step.
 
Paul said:
Actually, certain models of cooling devices, are notorious for
failing. And for good reasons.

On some AMD systems, the socket has three plastic tabs for the clip
to snap onto. And some genius heatsink designers, fit a "one-hole"
clip onto the plastic. And then apply extreme pressure on the clip.
After a couple years, the single plastic tab, snaps from the abuse.

There have also been cases, of some of the Intel plastic ones
snapping.
So it is possible for cooler parts to fail while in use, and
without mechanical shock being the reason for the failure. All
it takes, is plastic... and stress.

My current after-market cooler, uses screws and nuts. And I can
be reasonably assured it won't fall off.

The Northbridge cooler, is sometimes held in place with a
spring steel wire. And it hooks onto some U-shaped things
soldered to the motherboard. Due to the metal chosen for the
U-shaped thing, it doesn't solder well. (I have one design
here, that uses stainless steel for the hook, when a tin-lead
interface should have been used. They can pull out of the motherboard,
because of the lousy solder joint.) You can see an example
of a U-shaped thing, pulled out here.

http://sequimpc.com/images/IMG_1940.jpg
Click to expand...

Yes, you're right....those plastic retention frames for CPUs can break
in use, though it is fairly rare.

I haven't seen a Northbridge heat sink fall off....I'm wondering if it
was specific to certain mobo brands that used the inferior metal in the
clip.
 
glee said:
Yes, you're right....those plastic retention frames for CPUs can break
in use, though it is fairly rare.

I haven't seen a Northbridge heat sink fall off....I'm wondering if it
was specific to certain mobo brands that used the inferior metal in the
clip.
Click to expand...

The really strange part about those U-shaped things they used
on the motherboards, is someone at the factory *must* have
known the metallurgy was wrong. I spotted it, the instant
I got a new motherboard from that generation. I took one
look at the hook eye, and could see it wasn't tin/lead.
(And this was a tin/lead non-ROHS motherboard, so that
wasn't the issue.) Turning the board over, and looking
at the solder joint, you could see the solder wasn't
wetting the metal. Any staff involved in visual inspection,
must have noticed it. Usually they take that stuff
seriously. (They did at my PCB factory at work.)

Mine never fell off, but it's happened to plenty of other
people. And some of the Dells are neat, because the designer
at Dell, put an electrical continuity check, across the
metal wire holding the Northbridge. If the wire on a Dell
Northbridge comes loose, it stops the computer from running.
(Not on all models, just some of them.) Now, if someone was
clever enough to add that feature, it also means they knew
the stupid thing would fall out. Boggles the mind... Why
would you need such a check, if you did a good mechanical
design in the first place ?

Paul
 
The really strange part about those U-shaped things they used
on the motherboards, is someone at the factory *must* have
known the metallurgy was wrong. I spotted it, the instant
I got a new motherboard from that generation. I took one
look at the hook eye, and could see it wasn't tin/lead.
(And this was a tin/lead non-ROHS motherboard, so that
wasn't the issue.) Turning the board over, and looking
at the solder joint, you could see the solder wasn't
wetting the metal. Any staff involved in visual inspection,
must have noticed it. Usually they take that stuff
seriously. (They did at my PCB factory at work.)

Mine never fell off, but it's happened to plenty of other
people. And some of the Dells are neat, because the designer
at Dell, put an electrical continuity check, across the
metal wire holding the Northbridge. If the wire on a Dell
Northbridge comes loose, it stops the computer from running.
(Not on all models, just some of them.) Now, if someone was
clever enough to add that feature, it also means they knew
the stupid thing would fall out. Boggles the mind... Why
would you need such a check, if you did a good mechanical
design in the first place ?

    Paul
Click to expand...

Found the problem.

It was a program called TeaTimer.exe that comes with Spybot.

Seriously excessively use of the CPU.

Now, the computer is very quiet.

Andy
 
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