RxK
Thu Apr 10 07:22:01 PDT 2008
Thanks for your response. I was aware of much of what you say, ...and
completely agree with what I was't aware of !
...btw, I am an ardent ANTI-overclocker - much of what is in the discussion
forums i.e. people deluding themselves that they've achieved something
marvellous by overclocking, comments such as "...and very stable..." etc.
<ROFL>
I prefer the manufacturers specs., ...and was querying, as I see it,
unsatisfactory Intel stock heatsink compound behaviour, in relation to
maximising the lifespan of the cpu. Specifically, I suspect it was too
thick, or not "fluid enough" for the excess to squeeze out, as normally
happens. I've always applied the stuff thinly, and the excess that squeezes
out is not excessive, if you see what I mean.
anyhooo, to clarify, the stock thermal paste that was on the Intel stock hs,
and cpu "lid", had obviously cured to some degree and had not "spread"
enough to allow any metal to metal contact at all, as far as I could see,
which one would expect to happen. ...and I suggest it's not sensible to
remove the thing to check that it spread out satisfactorily - sort of
defeats the object of a satisfactory fitting !
I should have mentioned in my OP that bios / and Speed Fan reported the core
temperature, at idle, as 38 deg.C ...sometimes up to 45 deg. C under load.
Since replacing the Intel stock hs with an Aksa heatpipe cooler, it's 26
deg. C at startup, 30 deg. C atm - mostly idling.
regards, Richard
"VanguardLH" <V@nguard.LH> wrote in message
news:uasol0vmIHA.4076@TK2MSFTNGP05.phx.gbl...
> RxK wrote:
>
>> Sorry for being a bit off-topic but, surely there's lots of builders in
>> here.
>> I've built lots of boxes in the past and never really dabbled with
>> "super"
>> cpu coolers i.e. stock heatsink and fan always did a sufficient job.
>>
>> A few months ago I upgraded my faithful old XP2600 Barton Skt. A to a
>> D935
>> Conroe cpu, on a "Conroe" motherboard, and during lots of digging on the
>> web, at that time, noticed observations that the Pentium D's ran "hot"
>> compared to others. My "D" core always idled at approx. 38 degrees | 42
>> degrees under load. Yesterday I fitted a cheap Akasa triple heatpipe
>> cooler
>> and noticed that the thermal "paste" was quite soft. When I removed the
>> stock Intel heatsink it appeared that the thermal compound was quite
>> thick,
>> (obviously it had "cured"), but it hadn't spread out very much,
>> suggesting
>> that it was perhaps too thick, or "aged," when I originally fitted the
>> thing.
>>
>> I'm not going to try it just to satisfy my curiosity but, do you think
>> that
>> if I cleaned that up, and refitted the stock h/s with a good quality
>> thermal
>> compound, that it would run a lot cooler ?
>>
>> regards, Richard
>
> What do you consider "a lot"? Is 4C a lot to you? It isn't to me but
> then I am not overclocking and looking to squeeze out every Celsius
> degree in reduction possible because I'm pushing the temperatures up
> towards their maximums.
>
> Most home jobbers gob on way too much thermal paste. It should be
> transparent. The idea is to fill in the gaps, not insulate the heatsink
> from the die cover plate on the CPU. Air is bad for heat transfer.
> Metal-to-metal is best. Thermal paste is somewhere in between: not as
> bad as metal-to-air-to-metal but definitely not as good as
> metal-to-metal. You want to fill in the microscopic pores which contain
> air, not try to use the thermal paste for where metal-to-metal contact
> would've been made. After applying the thinly transparent layer of
> thermal paste, twist the heatsink atop the CPU to make sure you spread
> it out evenly before clamping it down. If you remove a heatsink and see
> a ridge of extra goop around an indent for the where the CPU cover was
> pressed, you used too much. You should just make out an outline of
> where the cover pressed against the heatsink. If you have a warped
> heatsink that doesn't mate well with the CPU cover, you'll have to lap
> the heatsink.
>
> Some pastes are deliberately made thicker to prevent home jobbers from
> gooping on too much, squeezing it out when clamping down on the
> heatsink, and having the excess squeeze out onto the CPU and dripping
> elsewhere to contaminate those other parts. In fact, you have to be
> careful with the silver metal pastes since they are conductive. Some go
> through a transition (phase change) when heated that changes their
> viscosity (which is no longer important after the surfaces have been
> mated since the paste won't get where there is metal-to-metal contact).
> Thermal pads are like that, too: they are in an amorphously fluid state
> that go through a phase change under pressure at elevated temperature to
> make them less viscous and allow reflow into the gaps. Phase-change
> here means the material changes viscosity, not that a liquid changes to
> a gas as is used in some heatsinks that use heatpipes. See
>
http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/26951.pdf.
>
> Different pastes have different transfer rates. The differences can
> amount to a few Celsius in temperature change, like maybe 4C to 6C. The
> silver paste might get you 2C more than the ceramic paste which gets you
> maybe 2C more than good general paste which gets you maybe 1C to 1C
> better than a thermal pad. Lapping the heatsink might get you another
> 1C to 2C. Some heatsinks come with a rather rough surface so lapping
> helps. Few come with a highly polished (minimal pores) and nearly flat
> base. If they are warped (where you see the paste is thicker in some
> spots than others after removing the heatsink and inspecting the pasted
> area), you need to lap the heatsink. You want as much metal-to-metal
> contact as possible rather than relying on paste to replace air.