COPPER CPU SHIMS: The Definitive Answer !!

Ok, my gut feeling was that installing a copper shim was a mod that could
provide measurable benefits. My reasoning was as follows: Presently my
Maze3 waterblock is only slightly warm at the edges of the block, indicating
a large thermal gradient between the center water channel and the outer
water channel, and thus plenty of cooling power still available if some heat
could be diverted to the outer portion of the waterblock, instead of simply
the 1cm x 1.5cm cpu core area (non-heat-spreader cpu).

Now, given that the cpu thermistor is on the other side of the substrate on
the botom of the cpu and is registering quite a high temp, and that the cpu
electrical traces (which permeate the substrate) most definitely are
significant thermal conductors, it seems very reasonable to me to conclude
that the opportunity is there to lower temps by this multiplication of the
surface area touched by the waterblock by probably 7x or 8x.

So. On my AthlonXP 1700+ running at 10.5 x 230fsb = 2.4ghz @ 1.9v cpu, I
installed a copper shim from www.1coolpc.com (I bought the XP shim, but it
required a lot of Dremel work to get it to fit -- I suspect this is
actually a Barton shim; but anyway). I was very careful to check that the
shim did not sit higher than the cpu core, to file all edges smooth, and to
check that the shim sat completely flat on the cpu substrate. In addition,
and this is an important touch, I smeared both sides of the shim with
ArticSilver5, a thin coat. Don't get careless and blow off this step as you
will compromise much of the effectiveness of the mod.

The results are extremely satisfying!! Immediately after installation
Prime95 has stabilized at 54C, probably 10C lower than previous, and after
curing will certainly drop even farther. Now, I hear the skeptics scoffing,
and realize that it's likely the thermal characteristics of the copper shim
are not the only factor for the dramatic improvement.

I suspect that other factor consists of the large-surface-area copper shim
forcing the (large and heavy) waterblock to lie completely flat on the cpu
core. Although I've always used a fiber washer, clearly it was not
preventing a slight rocking of the heatsink from one side of the core to the
other, which could be caused by unequal spring pressure or simply gravity.

Both of these factors make the copper shim a must-have addition to a
high-performance Barton or other non-heatspreader-type cpu installation,
IMHO. There is no doubt in my mind that people running very heavy heatsinks
like the SP-97 or big waterblocks will see an immediate temperature
reduction from careful installation of a copper shim.

rms

rms wrote:
[...]
The results are extremely satisfying!! Immediately after installation
Prime95 has stabilized at 54C, probably 10C lower than previous, and
after curing will certainly drop even farther. Now, I hear the
skeptics scoffing, and realize that it's likely the thermal
characteristics of the copper shim are not the only factor for the
dramatic improvement.

I know this is a bit more work, but the results would be significantly more
meaningful if you remounted the block several times, both with and without
the shim. I've noticed up to a ~5 deg C variation (as in +/- 3 deg C or so)
of diode temps when remounting a TT Silent Boost, so there's a good chance
the real change is reasonably different from what you got above. Finally, it
would be great if you could find a plastic (not mica, which is also a good
thermal conductor) shim and repeat. Most plastic shims are good thermal
insulators.

I suspect that other factor consists of the large-surface-area copper
shim forcing the (large and heavy) waterblock to lie completely flat
on the cpu core. Although I've always used a fiber washer, clearly
it was not preventing a slight rocking of the heatsink from one side
of the core to the other, which could be caused by unequal spring
pressure or simply gravity.

This would show up in repeated tests. Another thing that could be causing it
is that you didn't crank it as tight when you first mounted it (or it
loosened over time)without the shim. Again, repeated measurements would
demonstrate this.

One thing you might want to try, if you know people with the equipment
(local university or search and rescue, possibly?), is to take thermal
images of the block from above, with and without the shim. If your
temperature is accurate (and assuming water temp ~20 deg C), then a drop of
10 deg C implies that you have about 20% of the heat flowing through the
shim, which should definately show up on a thermal image.

[...]
--
Michael Brown
www.emboss.co.nz : OOS/RSI software and more
Add michael@ to emboss.co.nz - My inbox is always open

If your
temperature is accurate (and assuming water temp ~20 deg C), then a drop
of
10 deg C implies that you have about 20% of the heat flowing through the
shim

I did not imply this. If the difference is simply a result of a skewed
heatsink, the shim would show no temperature increase. I'm saying that a
copper shim gives dual benefits: a flatter more stable platform for the
heatsink, and additional surface area for heat dissipation. Where the
balance lies between those two I can't say.

rms

A slightly easier way to test would be to put a thermistor on the outer edge
of the heatsinks contact surface both with and without the shim.
--


"I don't cheat to survive. I cheat to LIVE!!"
- Alceryes

"rms" wrote in message
. ..
If your
temperature is accurate (and assuming water temp ~20 deg C), then a drop
of
10 deg C implies that you have about 20% of the heat flowing through the
shim

I did not imply this. If the difference is simply a result of a skewed
heatsink, the shim would show no temperature increase. I'm saying that a
copper shim gives dual benefits: a flatter more stable platform for the
heatsink, and additional surface area for heat dissipation. Where the
balance lies between those two I can't say.

rms

In comp.sys.ibm.pc.hardware.chips rms wrote:
as follows: Presently my Maze3 waterblock is only slightly
warm at the edges of the block, indicating a large thermal
gradient between the center water channel and the outer water

True if the center water edges are much warmer than the
outside edges. Did the outside edges warm up with the shim?

The results are extremely satisfying!! Immediately after
installation Prime95 has stabilized at 54C, probably 10C

No denying data. I wouldn't call prime95 very severe,
but I'm biased.

I suspect that other factor consists of the
large-surface-area copper shim forcing the (large and
heavy) waterblock to lie completely flat on the cpu core.
Although I've always used a fiber washer, clearly it was
not preventing a slight rocking of the heatsink from one
side of the core to the other, which could be caused by
unequal spring pressure or simply gravity.

Rocking or edge contact with a die-back is extremely
detremental to heat-transfer, even with high-k heat compound.
I always check for this and correct grease spreading by very
slightly rotating the HS after installation. I'm looking
for a very heavy, smooth drag. Any sign of scraping (other
than from the clamp) means trouble.

I suspect this was the biggest effect, but heat spreaders
can be useful (seen by a reduction in center/edge gradients
on the HS)

-- Robert author `cpuburn` http://pages.sbcglobal.net/redelm

If your 'old' temps were 64C with water cooling you obviously has something
seriously wrong with your installation. Even 54C is not great given that I'm
getting 44C with air cooling at 2640MHz / 1.93V (Abit NF7-S / XP-M 2500+ /
SP-97, no shim).
Shims make no significant difference to cooling performance, any properly
installed heatsink will already be sitting flat on the CPU anyway.

--
*****Replace 'NOSPAM' with 'btinternet' in the reply address*****
"rms" wrote in message
...
Ok, my gut feeling was that installing a copper shim was a mod that could
provide measurable benefits. My reasoning was as follows: Presently my
Maze3 waterblock is only slightly warm at the edges of the block,
indicating a large thermal gradient between the center water channel and
the outer water channel, and thus plenty of cooling power still available
if some heat could be diverted to the outer portion of the waterblock,
instead of simply the 1cm x 1.5cm cpu core area (non-heat-spreader cpu).

Now, given that the cpu thermistor is on the other side of the substrate
on the botom of the cpu and is registering quite a high temp, and that the
cpu electrical traces (which permeate the substrate) most definitely are
significant thermal conductors, it seems very reasonable to me to conclude
that the opportunity is there to lower temps by this multiplication of the
surface area touched by the waterblock by probably 7x or 8x.

So. On my AthlonXP 1700+ running at 10.5 x 230fsb = 2.4ghz @ 1.9v cpu, I
installed a copper shim from www.1coolpc.com (I bought the XP shim, but it
required a lot of Dremel work to get it to fit -- I suspect this is
actually a Barton shim; but anyway). I was very careful to check that the
shim did not sit higher than the cpu core, to file all edges smooth, and
to check that the shim sat completely flat on the cpu substrate. In
addition, and this is an important touch, I smeared both sides of the shim
with ArticSilver5, a thin coat. Don't get careless and blow off this step
as you will compromise much of the effectiveness of the mod.

The results are extremely satisfying!! Immediately after installation
Prime95 has stabilized at 54C, probably 10C lower than previous, and after
curing will certainly drop even farther. Now, I hear the skeptics
scoffing, and realize that it's likely the thermal characteristics of the
copper shim are not the only factor for the dramatic improvement.

I suspect that other factor consists of the large-surface-area copper shim
forcing the (large and heavy) waterblock to lie completely flat on the cpu
core. Although I've always used a fiber washer, clearly it was not
preventing a slight rocking of the heatsink from one side of the core to
the other, which could be caused by unequal spring pressure or simply
gravity.

Both of these factors make the copper shim a must-have addition to a
high-performance Barton or other non-heatspreader-type cpu installation,
IMHO. There is no doubt in my mind that people running very heavy
heatsinks like the SP-97 or big waterblocks will see an immediate
temperature reduction from careful installation of a copper shim.

rms

I suspect this was the biggest effect, but heat spreaders
can be useful (seen by a reduction in center/edge gradients
on the HS)

Heatsinks do perform differently when used with large-area vs.
small-area heatsources, as shown by any of the
http://www.frostytech.com/index.cfm reviews, and it seems evident to me that
waterblocks will always do better with a large-area heatsource.

-- Robert author `cpuburn` http://pages.sbcglobal.net/redelm

cpuburn does indeed raise cpu temps farther than prime95, in my case
about 4C higher. The reason I've always used Prime95 is the error-checking
that I know it does, which gives me a clear indication that I have a
problem. It's not clear to me that cpuburn has any error-checking?

rms

If your 'old' temps were 64C with water cooling you obviously has
something seriously wrong with your installation. Even 54C is not great
given that I'm getting 44C with air cooling at 2640MHz / 1.93V (Abit NF7-S
/ XP-M 2500+ / SP-97, no shim).
Shims make no significant difference to cooling performance, any properly
installed heatsink will already be sitting flat on the CPU anyway.

A typical lousy off-hand response. I'm running a 2yr-old xp, not a
mobile barton. And I suspect that *most* installations do not conform to
your definition of a 'properly installed heatsink'.

rms

--
*****Replace 'NAPALM'S with 'bitternut's in the reply address*****
"rms" wrote in message
. ..
If your 'old' temps were 64C with water cooling you obviously has
something seriously wrong with your installation. Even 54C is not great
given that I'm getting 44C with air cooling at 2640MHz / 1.93V (Abit
NF7-S / XP-M 2500+ / SP-97, no shim).
Shims make no significant difference to cooling performance, any properly
installed heatsink will already be sitting flat on the CPU anyway.

A typical lousy off-hand response. I'm running a 2yr-old xp, not a
mobile barton. And I suspect that *most* installations do not conform to
your definition of a 'properly installed heatsink'.

rms

Suspect what you want.... Maybe most of the ones you build are not properly
installed, in fact I'm pretty certain of it.
Certainly every system that I've ever put together achieves my definition of
'properly installed' (and I've built hundreds) and even the ones with stock
air cooling achieve temps similar to your water cooled ones.

I've also tried shim's and I know for certain they make no difference that
can be recorded .... unless you are comparing to a system built by an ape.

*****Replace 'NOSPAM' with 'btinternet' in the reply address*****
"rms" wrote in message
. ..
I suspect this was the biggest effect, but heat spreaders
can be useful (seen by a reduction in center/edge gradients
on the HS)

Heatsinks do perform differently when used with large-area vs.
small-area heatsources, as shown by any of the
http://www.frostytech.com/index.cfm reviews, and it seems evident to me
that waterblocks will always do better with a large-area heatsource.


rms
A shim does not increase the 'heat source' area... The only part of a chip
that produces heat is the core and without increasing the size of the
silicon you cant make the core area larger.
The CPU substrate produces no heat and is also a VERY poor conductor of heat
from the core, therefore the heat path from the core, thru' the substrate,
thru' the shim, thru the air gap (because the shim has a small clearance
between substrate and heatsink) and into the heatsink is virtually non
existant.