CPU heat sink staying cool - why isn't the CPU transferring its heat to heat sink?

[Dundonald]

Rod, thanks for the post. I didn't realise that a heat sink could be
put on the wrong way. I'll try spinning the heat sink and fan 180
degrees back around see if that makes any difference. Out of interest,
how can it make a difference, I haven't checked in detail but is the
top of the CPU and the base of the heat sink not flat so in either way
around they should both perform the same?

OK GREAT NEWS is that I think I have now fixed the problem. So you
know where I'm coming from it may be best to see the pictures here
http://www.moorcut.co.uk/cpu/cpu.html . Here's what I did. I took the
CPU heat sink and fan off, I took the CPU out its socket and cleaned
off the thermal paste. You'll notice from the pictures that there is
quite a lot of paste on the top of the CPU. I also cleaned a lot of
paste off of the bottom of the CPU heat sink. I also noticed that the
CPU heat sink was flat so I wasn't sure turning it around 180 degrees
would make a difference but I did so anyway. Fired the computer up,
ran the same old test that would usually cause a problem and BINGO -
the highest the CPU temperature got to was 38.5 degrees celcius!!!
Brilliant. As I've previously described it used to just shoot up to 60
degrees and switch off. I then ran the prime95 torture test for a
whole 17 minutes (got bored after that) and the maximum temperature
reached was 49 degrees celcius and the temp was pretty stable. So all
in all it seems good now. Well chuffed! Still not sure whether it was
the removal of the thermal paste (there's hardly any thermal paste on
either the CPU or the CPU heat sink now) or whether it was turning the
heat sink 180 degrees. Any ideas?

The last two questions I have just purely out of interest are:

1. what is the smaller heat sink on my mother board - can someone
confirm that it's a motherboard heat sink or not? It doesn't appear to
be connected to the CPU.

2. Something was switching my computer off at high CPU temperature,
what was it? I have checked every single option in the BIOS and can't
find anything. Anyone any ideas where to find this or what is in fact
doing it?

Thanks for everyone's help so far.

 

[Rod Speed]

Hi, as promised here's a few pictures of my motherboard, heat sink's
and CPU etc ... Can someone tell me if the small heat sink is the
mother board heat sink? Thanks.

Pictures are here: http://www.moorcut.co.uk/cpu/cpu.html

The problem with the possibility of having the cpu heatsink the
wrong way around isnt with the base of the heatsink, its with
how the mounting clips holding it on are done and that isnt
obvious from the pictures.

The smaller heatsink is indeed for one of the chips on the motherboard.

 

[Rod Speed]

Rod Speed wrote

Rod, thanks for the post. I didn't realise that a heat sink could be
put on the wrong way. I'll try spinning the heat sink and fan 180
degrees back around see if that makes any difference.

Out of interest, how can it make a difference,

The top of what the heatsink mounts to socket wise isnt necessarily
symmetrical, some arent so the bottom of the heatsink doesnt sit
flat on the cpu when its on the wrong way around.

I haven't checked in detail but is the top of the CPU and the base of the heat
sink not flat so in either way around they should both perform the same?

Its not that, just that what the heatsink mounts to on the socket may not be symmetrical.

 

[Rod Speed]

Dundonald wrote

OK GREAT NEWS is that I think I have now fixed the problem.

Teach me to not read all the new posts in a thread before replying |-(

But then I'm still doing that, so must be incorrigible |-)

So you know where I'm coming from it may be best to see the
pictures here http://www.moorcut.co.uk/cpu/cpu.html . Here's
what I did. I took the CPU heat sink and fan off, I took the CPU
out its socket and cleaned off the thermal paste. You'll notice from
the pictures that there is quite a lot of paste on the top of the CPU.
I also cleaned a lot of paste off of the bottom of the CPU heat sink.

That was likely the problem, too much of that old crud remaining.

You only need enough so that the pores in the metal on the top
of the cpu and the bottom of the heatsink are filled, and no more.

I also noticed that the CPU heat sink was flat so I wasn't sure turning
it around 180 degrees would make a difference but I did so anyway.

Fired the computer up, ran the same old test that would usually cause
a problem and BINGO - the highest the CPU temperature got to was
38.5 degrees celcius!!! Brilliant. As I've previously described it used
to just shoot up to 60 degrees and switch off. I then ran the
prime95 torture test for a whole 17 minutes (got bored after that)
and the maximum temperature reached was 49 degrees celcius and the
temp was pretty stable. So all in all it seems good now. Well chuffed!

Still not sure whether it was the removal of the thermal paste (there's
hardly any thermal paste on either the CPU or the CPU heat sink now)

Likely that was it.

or whether it was turning the heat sink 180 degrees.
Any ideas?

There is one obvious way to prove that.

The last two questions I have just purely out of interest are:

1. what is the smaller heat sink on my mother board - can
someone confirm that it's a motherboard heat sink or not?

Yes it is, heatsink for one of the motherboard chips.

It doesn't appear to be connected to the CPU.
Correct.

2. Something was switching my computer
off at high CPU temperature, what was it?

Can be the cpu or the bios.

I have checked every single option in the BIOS and can't find anything.
Anyone any ideas where to find this or what is in fact doing it?

If it isnt in the bios, its the cpu doing it by itself.

 

[Joel]

That was likely the problem, too much of that old crud remaining.

You only need enough so that the pores in the metal on the top
of the cpu and the bottom of the heatsink are filled, and no more.

My turn to ask some question <g>. I have seen some site (like newegg)
offers different thermal paste and different price etc.. Well, I was about
to buy a TUBE of one of the most expensive ones, but decided not too cuz I
don't believe more_expensive_is_better or may not be the right paste for the
job.

IOW, I have always used the paste came with the CPU, but because it isn't
so expensive and I don't mind to add it to the next order, but don't know
which works good for the CPU (just incase I need to work on the heatsink).

 

[Dundonald]

Rod Speed wrote:
<snip>

Thanks for your help Rod.

 

[Rod Speed]

My turn to ask some question <g>.

Tad radical, can end in tears before bedtime.

I have seen some site (like newegg) offers different thermal paste
and different price etc.. Well, I was about to buy a TUBE of one
of the most expensive ones, but decided not too cuz I don't believe
more_expensive_is_better or may not be the right paste for the job.

There's bugger all in it, they're all pretty much of a muchness.

IOW, I have always used the paste came with the CPU,
but because it isn't so expensive and I don't mind to add
it to the next order, but don't know which works good for
the CPU (just incase I need to work on the heatsink).

They're all fine from an operation like that.

 

[kony]

My turn to ask some question <g>. I have seen some site (like newegg)
offers different thermal paste and different price etc.. Well, I was about
to buy a TUBE of one of the most expensive ones, but decided not too cuz I
don't believe more_expensive_is_better or may not be the right paste for the
job.

IOW, I have always used the paste came with the CPU, but because it isn't
so expensive and I don't mind to add it to the next order, but don't know
which works good for the CPU (just incase I need to work on the heatsink).

The best compounds are those with longer life at higher
density heat loads, those with synthetic base oil instead of
silicone. The most popular are those made by Arctic Silver,
but another brand would do similarly well. In other words,
a degree or two temp difference shouldn't be significant,
the CPU shouldn't be that close to overheating, but how long
the compound lasts could be important if the system wasn't
meant to be torn down and thrown away in a couple years.

Newegg tends to charge a lot for compound (unless they've
changed their prices recently), I suggest Arctic Silver
Alumina or Ceramique from http://www.svc.com , a tube is $4
delivered,
http://www.svc.com/chidethcobya.html

 

[kony]

OK GREAT NEWS is that I think I have now fixed the problem. So you
know where I'm coming from it may be best to see the pictures here
http://www.moorcut.co.uk/cpu/cpu.html .

I can't tell for sure, but from the pictures it looks a
little bit like you left the original thermal interface
material on the CPU and maybe even the plastic liner...
referring to this picture,
http://www.moorcut.co.uk/cpu/10-12-06_1536.jpg

When using heatsink grease, the bottom of the heatsink
should be _completely_ clean of all of that. Some people
will even go a step further and lap the bottom of the
heatsink, but it's probably not going to help enough to
bother with on a CPU with a heatspreader integral.

You don't need that much thermal compound either, just put a
grain of rice sized blob in the middle of the CPU, smear it
around slightly if you want but it does not have to be
spread thickly to the edges of the heat spreader- excess
compound will, over time, spread out anyway due to the heat
and downward force on the heatsink while mounted. It tends
to take a few days and thermal cycles for the final temp to
stabilize, it'll run a few degrees warmer (low single-digit
difference) till then.

Here's what I did. I took the
CPU heat sink and fan off, I took the CPU out its socket and cleaned
off the thermal paste. You'll notice from the pictures that there is
quite a lot of paste on the top of the CPU. I also cleaned a lot of
paste off of the bottom of the CPU heat sink. I also noticed that the
CPU heat sink was flat so I wasn't sure turning it around 180 degrees
would make a difference but I did so anyway. Fired the computer up,
ran the same old test that would usually cause a problem and BINGO -
the highest the CPU temperature got to was 38.5 degrees celcius!!!
Brilliant. As I've previously described it used to just shoot up to 60
degrees and switch off. I then ran the prime95 torture test for a
whole 17 minutes (got bored after that) and the maximum temperature
reached was 49 degrees celcius and the temp was pretty stable. So all
in all it seems good now. Well chuffed! Still not sure whether it was
the removal of the thermal paste (there's hardly any thermal paste on
either the CPU or the CPU heat sink now) or whether it was turning the
heat sink 180 degrees. Any ideas?

I'd have to see the heatsink in person to be sure, but it
was probably too much grease since as you wrote, the
heatsink looks symmetrical, no ledge on it.

The last two questions I have just purely out of interest are:

1. what is the smaller heat sink on my mother board - can someone
confirm that it's a motherboard heat sink or not? It doesn't appear to
be connected to the CPU.

Chipset heatsink, often called northbridge heatsink.

2. Something was switching my computer off at high CPU temperature,
what was it? I have checked every single option in the BIOS and can't
find anything. Anyone any ideas where to find this or what is in fact
doing it?

Thanks for everyone's help so far.

Since I can't see your bios menu, it's kinda hard to say
where it is, but it shouldn't have been shutting off as low
as it did, if you find that setting you might set it a bit
higher, around 70C, as the CPU may still get up around
55C-60C at full load if room temp changes, other parts are
also at higher load meaning more heat produced in the case,
or dust accumulates on the case, fans, or heatsink.

 

[Joel]

The best compounds are those with longer life at higher
density heat loads, those with synthetic base oil instead of
silicone. The most popular are those made by Arctic Silver,
but another brand would do similarly well. In other words,
a degree or two temp difference shouldn't be significant,
the CPU shouldn't be that close to overheating, but how long
the compound lasts could be important if the system wasn't
meant to be torn down and thrown away in a couple years.

Newegg tends to charge a lot for compound (unless they've
changed their prices recently), I suggest Arctic Silver
Alumina or Ceramique from http://www.svc.com , a tube is $4
delivered,
http://www.svc.com/chidethcobya.html

Thanks for the information. The reason I ask about the difference because
one of my systems is usually running 24/7 or pretty close to around 360+
days out of 365 days/year so I may try a better compound on next system.

Yup! I did make a quick browse through the list of the thermal compounds,
but don't know the difference so I didn't order it with the mboards and cpus
(I ordered 4 mboards + CPUs and dozen of fans but no thermal paste).

... hahaha I was too busy reading the feedbacks from end users to remember
to send this message. I am back to www.newegg.com to read the feedbacks
<bg>

 

[Dundonald]

kony wrote:

Since I can't see your bios menu, it's kinda hard to say
where it is, but it shouldn't have been shutting off as low
as it did, if you find that setting you might set it a bit
higher, around 70C, as the CPU may still get up around
55C-60C at full load if room temp changes, other parts are
also at higher load meaning more heat produced in the case,
or dust accumulates on the case, fans, or heatsink.

Aye you're definately right and it's a good point. Unfortunately I
simply can't find this option in the BIOS anywhere. But I'm sure it
(the max temperature setting) has got to be configured somewhere and
I'd like to find it. My setup is:

BIOS: American Megatrends AMI BIOS version 0908
Motherboard: ASUSTek Computer Inc. A8N-VM
CPU: AMD Athlon 64 3200 (2000 MHZ) Venice S939

 

[Rod Speed]

kony wrote:



Aye you're definately right and it's a good point. Unfortunately I
simply can't find this option in the BIOS anywhere. But I'm sure it
(the max temperature setting) has got to be configured somewhere and
I'd like to find it.

Presumably its the cpu target temperature in the hardware monitor
and its rather poorly described or the shutdown temp is related to
that cpu target temp in some unspecified way like it shuts down if the
cpu temp is say 10 degrees over the target temp at max fan speed etc.

 

[Dundonald]

Presumably its the cpu target temperature in the hardware monitor
and its rather poorly described or the shutdown temp is related to
that cpu target temp in some unspecified way like it shuts down if the
cpu temp is say 10 degrees over the target temp at max fan speed etc.

The CPU target temperature in my BIOS is set to 35 degrees celcius.
May be the shutdown temperature is a % increase of that?

 

[paulmd]

The CPU target temperature in my BIOS is set to 35 degrees celcius.
May be the shutdown temperature is a % increase of that?

IT shouldn't be force shutdown until 70 deg C (or more).

 

[Rod Speed]

Rod Speed wrote

The CPU target temperature in my BIOS is set to 35 degrees celcius.
May be the shutdown temperature is a % increase of that?

Yeah, that's what I meant.

Its obviously possible to test that proposition, but
whether its worth the trouble now is a separate matter.

 

[kony]

The CPU target temperature in my BIOS is set to 35 degrees celcius.
May be the shutdown temperature is a % increase of that?

Check the board manual and set that temp such that it
doesn't shut down till about 70-80C... or if the system does
critical calculations, determine the temp threshold for
instability and have it shut down at that threshold... which
on a non-o'c system, should still be above 65C.

 

[Rod Speed]

Check the board manual and set that temp such
that it doesn't shut down till about 70-80C...

He already said that the manual doesnt say how to
do that and it isnt obvious in the bios how to do that.

He's right on both counts.

or if the system does critical calculations, determine the temp
threshold for instability and have it shut down at that threshold...

He already said that the manual doesnt say how to
do that and it isnt obvious in the bios how to do that.

 

[Dundonald]

He already said that the manual doesnt say how to
do that and it isnt obvious in the bios how to do that.

He's right on both counts.


He already said that the manual doesnt say how to
do that and it isnt obvious in the bios how to do that.

Aye. Thanks for your help guys. The only way I can test shutdown temp
is by increasing the target temperature. There's no documentation that
I can find, or obvious menu options in the BIOS, that says either here
is the option to explicitly specify shutdown temperature, or, what the
% increase of the target temperature is. So for example, target
temperature I have set to 35 degrees celcius. If shutdown temperature
is 65 degrees celcius that's an 86 % increase on the target temperature.

 

[paulmd]

Aye. Thanks for your help guys. The only way I can test shutdown temp
is by increasing the target temperature. There's no documentation that
I can find, or obvious menu options in the BIOS, that says either here
is the option to explicitly specify shutdown temperature, or, what the
% increase of the target temperature is. So for example, target
temperature I have set to 35 degrees celcius. If shutdown temperature
is 65 degrees celcius that's an 86 % increase on the target temperature.

Has no one yet asked you what motherboard you have?
Now would be the time.

 

[paulmd]

Aye. Thanks for your help guys. The only way I can test shutdown temp
is by increasing the target temperature. There's no documentation that
I can find, or obvious menu options in the BIOS, that says either here
is the option to explicitly specify shutdown temperature, or, what the
% increase of the target temperature is. So for example, target
temperature I have set to 35 degrees celcius. If shutdown temperature
is 65 degrees celcius that's an 86 % increase on the target temperature.

Has no one yet asked you what motherboard you have?
Now would be the time.