On Thu, 15 Apr 2004 15:16:07 -0400, Robert Myers <>
wrote:
>>I assume all the AMD socket A processors are too hot-running for a project
>>like this. From what I can tell, the mobile processors use just as much
>>power as desktop processors unless you get an ultra-low-voltage processor
>>and the mobo can supply the correct voltage.
>>
>I've cross posted your question and my response to
>comp.sys.ibm.pc.hardware.chips so one of the local amdroids can tell
>both of us how clueless we are for even thinking of buying an Intel
>processor. ;-).
Yup, totally clueless! :>
Actually the assumption above is not entirely correct. Not only are
there some rather low powered AMD AthlonXP chips (they have pretty
similar power consumption to the Pentium-M and lower power consumption
than the P4-M), but also mobile chips do NOT use the same amount of
power as desktop chips, even at the same voltage.
A lot of power requirements can be tuned during the manufacturing
process. For high-end desktop chips the fabs are usually tuned for
high clock speeds. For low-end/low cost chips they are tuned for high
yields. For mobile chips they are tuned for low power.
The end result is that an AthlonXP 1700+ and an AthlonXP-M 1700+ could
have quite different power consumption figures, even if they are run
at the same voltage and at least superficially produced on the same
fab (ie both "Thoroughbred" cores made on a 130nm process). In fact,
AMD actually sells *THREE* AthlonXP-M 2000+ processors, all with
different power consumption figures. That's in addition to the old
AthlonXP (desktop) 2000+ chips that are no longer being sold.
Intel does pretty much the same thing with their P4 chips. The
desktop Pentium4, the "Mobile Pentium 4" and the "Mobile Pentium 4-M"
are all produced from the same basic die on superficially the same
process, but that process is tuned for different parameters and the
resulting power consumption figures for those chips is different. For
example, a desktop P4 2.4GHz has a Thermal Design Power (TDP) ranging
from 57.1W to 66.2W, depending on the model. The Mobile P4 2.4GHz
had a TDP of 59.8W, while the Mobile P4-M 2.4GHz has a TDP of either
30W or 35W.
For AMD's chips, I seem to recall that they defined a TDP of 60W for
all of their AthlonXP-M "Desktop Replacement" chips, while they
defined a TDP of 45W for all of their AthlonXP-M "Mainstream" chips
and 25W for their AthlonXP-M "Low power" chips. The problem with AMD
chips is that their documentation is absolutely abysmal when it comes
to mobile chips. I have no idea if it's even possible to tell a "Low
Power" chip from a "Desktop Replacement" chip (aside from the fact
that the fastest "Low Power" chip is a 2100+ model while the "Desktop
Replacement" parts go up to 2800+).
The main advantage to the AMD chips is two fold. First is that they
are all socket A chips, so you can drop them in any old Socket A
motherboard. Many of the mobile Intel chips come in all sorts of
custom sockets designed specifically for laptops. The second
advantage to AMD's line is that they are widely available. You'll
have a HELL of a time finding any mobile Intel chips, but mobile AMD
chips are sold from most of the bigger on-line vendors these days.
I'm fairly certain that the chips being sold are "Mainstream"
AthlonXP-M chips, but as mentioned above, it's damn near impossible to
tell them apart.
In the end though, when you get right down to it, the original idea
was probably the best. A "Tualatin" Celeron chip combined with a PCI
USB2 card should be the ticket. They consume about 30W of power,
should be fairly cheap and not all that difficult to find. You might
actually be able to find a Socket 370 board from VIA with USB2 built
in. Since VIA is still producing Socket 370 processors they are also
producing current Socket 370 motherboards. However given that a PCI
USB2 card should only cost you $10 or so, it's probably worth buying
one and sticking it in an Intel-based motherboard rather than
bothering with VIA chipsets and the odd-ball problems that all too
often accompanies said chipsets.
-------------
Tony Hill
hilla <underscore> 20 <at> yahoo <dot> ca
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