[KLUG Hardware] Re: Heat Sink compound -- exposed FC-PGA v. w/heat spreader

[Bryan J. Smith]

Quoting randall perry <randallp@domain-logic.com>:
> You gotta watch it with the large PPro or older Xeon (huge processors). 
> With such a large area you have to use a thermal pad or mesh-reinforced
> paste.

???

> Yeah, the core is too tiny to pump that much heat away from the
> processor

Er, it's a give/take relationship.  The reason why you want to make sure you
have grease on the outside of an exposed flip-chip is to _increase_ the total
surface area of any transfer, because the area is so much smaller than one with
a heat spreader atop (like newer P4s).

But an exposed flip-chip _without_ a heat spreader actually _increases_ thermal
transfer by an average of 2-3 degrees C.  Why?  Because there is _nothing_
between the die and the heatsink, other than an extremely thin plastic covering.

Several enthusiast sites have backed this up with testing of P4 chips without a
heat spreader, as well as AMD chips with an added "copper cap."  Which is why
AMD is continuing to release FC-PGA processors without a heat spreader, unlike
Intel.

> Yeah, the Artic is good shtuff.
> They don't use silicon in their compound and they actually screen more
> than one size of ceramic dust through so that you get better arranged
> particles (and better heat transfer).  It also cleans up pretty easy. 
> Not like that crap dot of compound you get with your heatsink (or
> thermaltape)

Correct.


-- 
Bryan J. Smith, E.I. (BSECE)       Contact Info:  http://thebs.org
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