With regard to how much power these Athlon XP mobiles draw, I'm guessing
that the fact that they are all rated at 45 watts is due to the difference
in speed not being that great (1800 - 2000 MHz) and that they all use 1.45v.
While the 2GHz model probably does draw a bit more power, it apparently
isn't that much more.
I sort of tested this out by running my processor at 1.8GHz with 1.45v and
then at 2.0GHz with 1.45 to see how the temperatures compare. I'm using an
Alpha PAL8045 heatsink and a 3700rpm 80mm fan. Room temp was about 74 deg.
F. I ran Prime 95 for about 10 mins to get a quick check on what the
temperature was under load.
1.8GHz @ 1.45v Idle: 96 F Load: 104 F
2.0GHz @ 1.45v Idle: 98 F Load: 107 F
The faster processor is a little warmer, but not by much.
On the other hand, run this processor at the default desktop voltage for the
Athlon XP and see what happens.
2.0GHz @ 1.65v Idle: 107 F Load: 120 F
And, if you are overclocking . . .
2.31 GHz @ 1.65v Idle: 112 F Load: 123 F
Increasing the voltage to get even higher speeds quickly translates into
even higher temperatures.
So, what this means, with regard to heatsink recommendations, is that if you
are running your XP mobile at its default voltage, just about any Athlon XP
heatsink rated for use with a Barton processor will do. I generally tend to
prefer larger heatsinks that can run larger and lower rpm fans, to limit the
fan noise. While I need a 3700 rpm fan in order to run my processor
overclocked with 1.65v, I could easily turn down the fan speed down, if I
was running the processor at only 1.45v. (Using this processor at it's
default voltage with a large heatsink and low rpm fan seems like a natural
starting point for putting together a quiet, multi-media, entertainment
center PC.)
For overclocking, the biggest heatsink your motherboard and case have room
for will be the best. ;-) Since these heatsinks can be quite heavy,
weighing in at over a pound for the largest all copper models, I recommend
looking for a heatsink and motherboard combo that allows you to use the four
mounting holes around the processor socket that some Athlon motherboards
have. Unfortunately, the reference design spec for Athlon XP processor
motherboards only called for heatsinks that clip to the socket; so, not all
socket A motherboards have these holes; and even if they do, they may not be
clear of small components mounted in the same area. This means you'll need
to check the heatsink manufacturer's compatibility list carefully before
assuming that you can mount their heatsink directly to your motherboard of
choice.
Because most manufacturers of Nforce2 400 motherboards put the processor
socket very near the edge of the board, some of these larger heatsinks will
overhang the edge of the board. So, you'll also have to make sure that your
case allows enough clearance between the motherboard and the bottom of the
power supply to accommodate this. (I'm thinking of the Zalman and
Thermalright heatsinks in particular.)
I went with the Alpha 8045 heatsink because it mounts to the motherboard and
it does not overhang the edge of the MB (my case has a brace below the power
supply and close to the edge of the motherboard, which I thought would
interfere with the larger heatsinks). I think the Alpha 8045 has been
replaced by the Alpha 8055 which is slightly larger (taller) and now adds
the option of either being clipped to the socket or being mounted directly
to the motherboard (if there are those 4 mounting holes). (There were some
minor compatibility issues using the Alpha on my Epox motherboard, which
required me to trim some nylon washers to fit around some MB components that
were too near to the mounting holes.)
The Zalman CNPS7000A-AlCu heatsink is a larger heatsink that is relatively
quiet but efficient enough at cooling that it can be used when overclocking.
There is also an all copper version of this heatsink.
Thermalright seems to be the epitome of massive air-cooled heatsinks. There
models are typically all copper; so they are quite heavy. There's the
standard design SLK-947U and the SP-97, which adds heatpipes; both of these
are very popular with the serious overclocking crowd.
Another design that is beginning to become popular makes use of a heatpipe
core, surrounded with cooling fins, and a fan on the side. The Aerocool
DP-102 was the first of this design that I was aware of, but I think others
are doing something similar, now.
I'm sure there are many other good heatsinks out there; so, consider those
mentioned above as a place to start. I think they are popular enough that
they provide a bit of reference point for comparison with other heatsinks.
John Sproule
----- Original Message -----
From: "Michael Eisenstadt" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, May 17, 2004 3:14 PM
Subject: Re: [PCBUILD] AMD XP vs Pentium 4
[Michael was asking about the power drawn by Athlon XP mobiles, as well as
heatsink recommendations for these processors.]
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