Copper Shims - Any good

Christopher Rawlison wrote:
Michael Brown wrote:

rms wrote:

I wouldn't bother. They're meant to "prevent" the core from being
crushed due to too much pressure from the heatsink.

You are neglecting the potential additional heat transfer of cpu
heat from the substrate to the heatsink with a copper shim.

Actually, it's the reverse. The substrate has a much higher thermal
resistance compared to copper (or aluminium), so at any particular
point on the substrate, the HSF surface above it has a higher
temperature. So you'd actually be dumping heat back into the
substrate, though in any case there isn't much conduction/convection
away from the substrate, so there would be a negligible performance
difference.

Actually, a shim does NOTHING for thermal transfer. Think about it
this way: when was the last time you felt the actual ceramic base on
a chip? It stays comparatively cool.

First of all, it's not ceramic. Ceramic went out with the Thunderbirds and
early Palominos. The current XP's are on an "organic" substrate, whatever
that means. The substrate on my XP2500's does get noticably warm after it's
been on for a while.

Secondly, the substrate has a high thermal resistance, so could be called a
thermal insulator (a thermal insulator is anything with a high thermal
resistance, and a conductor is one with a low resistance, high and low being
rather subjective). This does not mean that it won't heat up. All it means
is that heat will not flow through the material quickly, in the same sense
as current flowing. In the electrical sense, you can have a device with a
high resistance (thermal resistance) but also have it at a high potential
voltage (temperature). As long as there is a low heat loss through
conduction and convection, the substrate will heat up. This is why socket
sensors report a somewhat accurate temperature. However, this high thermal
resistance means the heat-carrying capability of the substrate is quite low,
which is why there is (or should be) a negligible temperature
increase/decrease compared to not using a shim.

[...]
Also you should be careful about putting any type of
thermal interface material on a shim that is conductive for the
simple fact that XPs have bridges on the ceramic that could get
shorted by the TIM.

That's what a drill press is for Seriously though, modifying a shim is
not recommended as it's very easy to warp it, which leads to bad die-hsf
contact. I beleive there's pre-machined copper shims for the new XPs that
have holes around the bridges, so as long as you're careful with the goop
(and ideally use silicon goop) there shouldn't be any problems.

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

You have to be careful ordering shims, as XP shims are different from Barton
shims. I believe I got my copper shim from www.1coolpc.com

rms

rms wrote:
You have to be careful ordering shims, as XP shims are different from
Barton shims. I believe I got my copper shim from www.1coolpc.com

Bartons are XPs

Perhaps you mean the difference between
ThunderBird/Palamino/ThoroughBred/Barton

Ben
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You have to be careful ordering shims, as XP shims are different from
Barton shims. I believe I got my copper shim from www.1coolpc.com

Bartons are XPs

Correct me if I'm wrong, but aren't Barton cores larger than XPs,
primarily because of the increased cache.

rms

rms wrote:
You have to be careful ordering shims, as XP shims are different from
Barton shims. I believe I got my copper shim from www.1coolpc.com

Bartons are XPs

Correct me if I'm wrong, but aren't Barton cores larger than XPs,
primarily because of the increased cache.

Bartons ARE XPs!!!

The Bartons are bigger than the Thoroughbreds due to increased cache.

The Thoroughbreds are also XPs.

Ben
--
A7N8X FAQ: www.ben.pope.name/a7n8x_faq.html
Questions by email will likely be ignored, please use the newsgroups.
I'm not just a number. To many, I'm known as a String...