hsf modding

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how safe is it to put a something like blu-tac on a cpu?

If anyones ever worked with Socket A cpu's you would be used to seeing the
little 4 pads that stop the hsf from resting on the cpu die. I need to make
something like this, or at least that serves the same purpose or an old skt
370 celeron 1Ghz coppermine. I'm trying to build a file server and need a
slightly quieter hsf than the 5000RPM! thing thats there now, i plan to use
an old stock amd sempron hs either fanless or with a fan(dependant on
testing!!), of course i don't want a crushed die.

any advice is helpful, thanks.

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Re: hsf modding

Veritech wrote:

"  If anyones ever worked with Socket A cpu's you would be used to
seeing the little 4 pads that stop the hsf from resting on the cpu die.
I need to make something like this, or at least that serves the same
purpose or an old skt 370 celeron 1Ghz coppermine.  "

Blu-Tac is going to squash, melt, and then offer no support for a
heatsink.  You may end up damaging the CPU die.  Go to a stationary shop
and buy some double-sided sticky pads.  I think either Blu-Tac or
Pritt-Stick make them.

Re: hsf modding

On Mon, 11 Apr 2005 15:12:10 GMT, "Veritech"

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Probably less safe than putting nothing on it.

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That's one way of putting it I suppose, but mostly they aid
in installing the heatsink, so it's at least semi-flat
against the core when being clipped down so it reduces the
changes of chipping the edge/corners of the core.

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CPUs generally come with these pads, did you remove the pads
from the intended CPU?

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IMO, it's a waste of time trying to put a passive 'sink on a
1GHz Celeron.  For one a 'sink made to use a fan is designed
differently than one meant to be passive. For another the
Celeron isn't hot-running but still above the thermal
envelope for normal passive cooling (even with a very large
Skt.A 'sink.  Far easier and more reliable to use a fan at
very low RPM, and that will help cool the motherboard too.

The original pads were foam with sticky-tape on them.  You
could put your own foam on but it's important that it be
near exactly the same thickness.  If too thin it doesn't
serve it's intended purpose and if too thick, decreases
pressure of interface between core and 'sink.

If you are careful installing the heatsink you should be
able to use CPU without the pads, providing the 'sink has a
properly working clip such that it does exert even force on
the center of the die... and if it doesn't, you ought to
seek a different 'sink regardless of whether there are pads
on the CPU or not.

Re: hsf modding

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I have a couple of AMD Socket A CPUs in on of my machines and the HSFs go
nowhere near those little foam rubber pads - moral of the story, check
carefully that any padding is actually needed there on your skt 370 Celeron
because it may not be. As for whether its passively cooled or not, I agree
with Kony that there should be a fan. I have a 933 MHz Slot 1 Pentium 3 in
another of my machines and I bought it second hand with a passive heatsink
attached from a Dell server. The case in that machine had fan air especially
ducted over the CPU area though so they'd obviously calculated the 30 or so
watts each CPU used was to much to dissipate with passive cooling. If you're
concerned about noise then use a larger slower turning fan with something
like one of those "flower" coolers available at quietpc.com.


Re: hsf modding

i'm pretty sure i will do, the heatsink retention clips are horizontal when
the motherboard is installed in the case, meaning that gravity forces the
heatsink  to lean down/inwards, thereby either chiping the cpu die or
damaging it without support. The older skt 370 hsf is alot lighter than the
skt a version plus the socket only has 2 lungs not 3 on each side, so i need
something other than the die to support its weight.

as for the passive cooling idea, i wasn't going to install it fully fan
less, i installed a temperature controlled fan in the front intake, and was
going to cut a hole in the back for either a 120mm or another 80mm
temperature controlled fan. so i would have an air flow pattern going right
over the hsf.
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Re: hsf modding

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Even though there's only 2 lugs per side, as long as you're not travelling
with the machine's motherboard vertical, it shouldn't be a problem (even
with a "gigantic" socket A HSF). The reason is because the sideways/angular
forces wouldn't be enough to displace the HSF enough that its body would
come into contact with the non-die part of the CPU. Remember that the die
part of a cpu is raised slightly above the other surrounding part on both
socket A and 370 CPUs.
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This sort of arrangement may not be "direct" enough though - if you made up
a duct pointing directly at the HSF from the fan(s) then that would be fair
enough but I wouldn't trust the natural circulation of air through a case
(even with an inlet and outley fan) to take away enough air from a Sempron
CPU cooler that was designed in the first place to have a fan mounted on it.
"Forced" air is whats needed. For the relatively small cost of a decent
quiet skt 370 HSF, I don't know why you just dont buy one of them and keep
your skt A Sempron HSF as a spare.


Re: hsf modding

On Mon, 11 Apr 2005 19:29:25 GMT, "Veritech"

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Isn't that a bit of an assumption?
Remember that the clip only secures the sink in that one
tiny center area if designed properly.

If the clip's center portion, that which contacts the top of
the 'sink itself, is round like most of intel's earlier
metal clips were, it' s a non-issue as round "knows not"
whether the clip is horizontal or vertical.  

If the clip  contact point is more of a bent, linear shape,
then the horizontally oriented clip actually does better
than one vertical, because it positions that linear contact
point in a vertial direction.  

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I suspect that either you're assuming this without having
tried it, or the clip itself is mis-engineered.

If the clip does exert force in the nearly-exact center, it
will not chip the die or damage it.  That would only happen
while installing it.  As for transportation of the system,
this may be a different story, in such a situation I would
not subject the system to any significant forces beyond
simply carrying it from one place to another with a normal
degree of care.

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yes, "over" it.  Not same thing.
You need a ductwork forcing a very large percentage of the
airflow though the 'sink, and a 'sink optimized for this-
which would have pin-fins or very tall, narrow, cross-cut
fins.  Just take our word for it, you are making things very
hard on yourself for no reason if you deviate from the
simple and time-tested solution of using a standard
'sink-fan combination then lowering fan speed as
appropriate.  It will also be quieter.  To get a rear
exahaust fan to cool the CPU it would have to generate a
higher flow rate (or still RPM due to the forepressure of
the ductwork channeling the airflow) than the rest of the
system actually needs.  Thus you have a fan on the wall of
the case producing more noise than the interior fan would
and being on the wall, the noise it produces escapes the

I've build overclocked Tualatin Celeron systems @ 1.6GHz
that are inaudible with fanned heatsink. Certainly a stock
speed Celeron 1.0 is easier still.  You wouldn't even need a
large Socket-A generation 'sink on that, a high quality
'sink (having thick aluminum on the bottom) can be quite
small and still sufficient.

See the 'sink on this northbridge:

It's cut-down slightly, one row of tines came off each side,
but it's nearly same size as original.  I used to buy those
'sinks by the case, they're Foxconn something-or-other (fan
was different than one in pic though).  Even that small
'sink is quite adequate for quietly cooling a Celeron 1.0GHz
with a 60x25mm 900 RPM fan on it... it would be inaudible in
all but the poorest of thin/misformed chassis.

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