So what if thermal compound spreads?

On Mon, 12 Apr 2004 10:47:11 +0100, Piotr Makley wrote:

Conor wrote:

Hmmm greasy finger goop, damn boy if you worked in my place
and used your bare hands you'd be getting a **** round the
back of your head...

Why is that? Is it because you buy into the hype of the
anti-static wristband manufacturers lies?

And yes I know all about static damage...


I don't think he is referring to damage by static. I think there
is something "bad" about even a trace of grease like that from a
finger. I don't know why this is though.

Can anyone enlighten me (gently)?

Short term, skin oils are a poor heat conductor, so interfere with heat
transfer from cpu to heatsink. Long term most peoples skin oils are acidic
or salty enough to cause corrosion, which is also not a good thing to have
between a cpu and a heatsink

JT

"QBall" wrote in message
...


It is hard to judge the exact amount. Rather than put too little
on and run the risk of not conducting heat away from the core,


You clearly have no understanding of thermal transfer, which is maximised
via metal-metal contact.
You fall into the ingenue's trap of believing more is better, when it fact
less is more.

And you fall into the trap of not understanding what thermal paste is used
for in the first place. It doesn't matter how much TP you use. The
pressure of the clamps holding down the heatsink will press out all TP
possible, while maximizing metal-to-metal contact. There will be no more
and no less metal-to-metal contact whether you use TP or not. The only
difference TP makes is that everywhere there is NOT metal-to-metal contact,
there will now be TP instead of air. If you use too little TP, you will not
get optimal heat transfer. If you use exactly the right amount of TP
(impossible), you will get optimal heat transfer. If you use too much TP,
you will get optimal heat transfer. The layer will be the same after
pressure is applied.

"Piotr Makley" wrote in message
...
"rstlne" wrote:

You don't say why it's inefficient !
Do you mean wasteful or something else constituting
inefficient. A vague and meaningless answer.

He means heat transfer will not be as good due to the large
gap between the core and the heatsink (I think large is a good
word because much of this is discuss'd on a "microscopic
level"


If the goo squishes out then presumably the layer of goo is no
thicker or thinner than if it didn't squish out?

That is correct. If that were not correct, then it would mean that the
"microscopic level" did not in fact cover every little nook and cranny. It
the force of the heatsink being held tightly against the CPU that make the
layer thin, not the amount that you use to begin with. There are only 2
amounts of thermal paste that you can use, from the perspective of the
heatsink/CPU inter-layer: enough, and not enough.

"Jim" wrote in message
news:x%%dc.5643$HN3.3117@fed1read07...
But having too much paste indicates another problem. The paste is ONLY
there to fill the microscopic imperfections between the mating surfaces.
If
those surfaces were perfect, you wouldn't even need the paste, in fact, it
would *hinder* heat transfer. If you have so much paste on the mating
surfaces that installation causes much of it to squeeze out, it indicates
you have too much paste! Think of it this way, if we could use the paste
to
fill ONLY the imperfections, that would be ideal.

But since that is impossible, it's a moot point. There are only 2 options -
not enough or too much.

Every bit of paste that
*interferes* with contact between the CPU and heatsink is working
NEGATIVELY
against heat trasnfer. We're only interested in preventing VOIDS between
the mating surfaces. Anything that's NOT filling the voids and is
actually
*preventing* surface to surface contact between the CPU and heatsink and
thus *hindering* heat transfer, not helping.

Pressure from the clamps will squeeze out all extraneous paste. Paste is
much softer than metal.

"Paul Hopwood" wrote in message
...
CrackerJack wrote:

What exactly is the problem if too much cpu compound is put on the
core and it gets squashed out onto the surrounding area?

Apart from looking messy, is there any real problem with this?

You'll always get a little but if you are squeezing a lot out it
indicates you've applied far too much, meaning the layer of paste
between the processor die/heatspreader and heatsink is too thick.

The pressure from the heatsink clamps won't allow a "layer" to be formed.
Metal will be pressed against metal wherever possible, and there's nothing
you could do to stop it if you tried.

"QBall" wrote in message
...

The reason for that is that you have no idea what you're talking about.
Until they dry out, vegemite and toothpaste work better than AS3 !

a) no they don't, not technically. Toothpaste has "grit" in it, so
theoretically it can't be as good (the "grit" particles are too big). (The
ability to measure this difference is another matter.)
b) "Until they dry out" - well that's going to happen, isn't it? So it's
not as good, is it? I'll tell you what - a cheeseburger works just as good
as AS3 - UNTIL YOU TURN YOUR COMPUTER ON.

"QBall" wrote in message
...

And it's so thick, there's no metal-metal contact.

Thick? Like viscosity? Then you have bad paste for this application.

"Noozer" wrote in message
news:ymoec.80914$Pk3.59130@pd7tw1no...

1) Wrong becausewhen you use too much compound, pressure will not squeeze
out to the same amount as if you had used the correct amount of compound
to
start with.

It is impossible to use exactly the correct amount to begin with. You must
either use too much, or suffer reduced heat transfer.

On Mon, 12 Apr 2004 13:19:12 GMT, JT wrote:

On Mon, 12 Apr 2004 10:47:11 +0100, Piotr Makley wrote:

Conor wrote:

Hmmm greasy finger goop, damn boy if you worked in my place
and used your bare hands you'd be getting a **** round the
back of your head...

Why is that? Is it because you buy into the hype of the
anti-static wristband manufacturers lies?

And yes I know all about static damage...


I don't think he is referring to damage by static. I think there
is something "bad" about even a trace of grease like that from a
finger. I don't know why this is though.

Can anyone enlighten me (gently)?

Short term, skin oils are a poor heat conductor, so interfere with heat
transfer from cpu to heatsink. Long term most peoples skin oils are acidic
or salty enough to cause corrosion, which is also not a good thing to have
between a cpu and a heatsink

JT

Nonsense. NOBODY has enough oil on their fingers to significantly cause
corrosion or degrade the cooling efficiency. Now maybe if someone had
just finished picking their nose or painting a fence...

"JT" wrote in message
s.com...
On Mon, 12 Apr 2004 10:47:11 +0100, Piotr Makley wrote:

Conor wrote:

Hmmm greasy finger goop, damn boy if you worked in my place
and used your bare hands you'd be getting a **** round the
back of your head...

Why is that? Is it because you buy into the hype of the
anti-static wristband manufacturers lies?

And yes I know all about static damage...


I don't think he is referring to damage by static. I think there
is something "bad" about even a trace of grease like that from a
finger. I don't know why this is though.

Can anyone enlighten me (gently)?

Short term, skin oils are a poor heat conductor, so interfere with heat
transfer from cpu to heatsink. Long term most peoples skin oils are acidic
or salty enough to cause corrosion, which is also not a good thing to have
between a cpu and a heatsink


Everything depends on the amount of skin-oil.
If you've recently washed your hands, very little will be deposited.
Some people barely secrete any oil, others have greasy skin.
Ultimately, the tiny amounts involved are unlikely to find their way onto
the sink because they'll be trapped under a layer of goop on the finger.



JT