On Sat, 15 Feb 2003, Russell McMahon wrote:

*>Anyone here have any REAL figures?

The last time I played with this it was P3 vs. K6. The K6s ran cooler. At
the time CPU dissipation ran at about 70W for AMD and 85W for Intel. The
heatsink temperature was to stay below 72C or so (65C was a safe target
but most people would prefer 55C at up to 40C ambient). Neither CPU would
survive the lack of a fan for more than a few minutes, but depending on
computing load, the heating varies very much (10:1). Both CPUs run
lukewarm w/o heatsink at idle load on several OSes (but not on W95 which
did not use the halt cycle at the time). Testing must be done with equal
computational load. There are programs for this and tests published at
that hardware site (tomshardware ?), and in some computer mags.

Now they have thermal shutdown in the bios so the meltdowns that used to
happen cannot happen anymore.

In general comparing temperatures like this is comparing apples with
oranges since the cache sizes etc vary greatly between chips, plus there
are chips of different technology (feature size - eg. 0.15u, 0.12u etc) on
the market, and all these things affect power consumptio. The lower
feature size lowers capacitance and with that power. More transistors
raise the power requirements. Usually for chips of the same technology and
cache size etc AMD draws less power by 10-20%. I think that this comes
from their being usually 2nd in the market with a specific product which
allows for greater optimisation, and from using smaller acches in general.
I do not know if it is true now.

I know for sure that certain models of K6 run significantly hotter than
others, although they have lower clocks. This is one of the technology
jumps probably. E.g. a 233MHz K6 would run hotter than a newer 450MHz one.

The temperature figures in your quoted posting are probably from a reentry
vehicle's outer surfaces or from inside a plasma torch. If you try to
arbitrarily place decimal points in them to get more reasonable figures
(eg 84.x instead of 84xx then the Intel cpu temp would be more like 100.0F
which would be above the 84.xx for the AMD - but this is just a guess).
1000F is about 500 deg. C and at that temperature only some special
downhole parts might work (nuvistors etc), certainly no cpu you can buy
for $100.

Peter

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