RE: [SLE] AMD running too hot

14 Aug 2001

      The main purpose of system cooling is to expel hot air quickly rather
than draw in air of room temperature (which is not cool but about 20C)
which soon heats up and then convects around the case. The main research
on this is from AMD themselves who have produced a guide to try and help
people preserve their Athlon-based systems. They found that many
front-case systems basically recirculate hot-air convecting inside the
case over the mainboard, in the worst scenarios.
Also, remember that an exhaust fan will necessarily produce the effect
of sucking air in to the box indirectly through the many air gaps in the
case (otherwise you'd quickly end up with an internal vacuum).

However, bear in mind that what I am saying is primarily for people who
have a front fan but no exhaust fan (not counting PSU).
If you do not have an exhaust fan and do not want to shell out for
another fan then you would be better off fitting the front fan as an
exhaust fan instead.
However, considering most systems are worth far more than the paltry
number of $$$ it costs to buy a new fan, it would make most sense to
simply add an extra fan to the rear. The main thing is to have an
efficient means of getting hot air out of the box, rather than merely
drawing warmish air in to it (I'm assuming most of us here have central
heating and don't live in igloos). 

Tim Harrell
...
-----Original Message-----
From: Peter Hollings [mailto:phollings@mediaone.net]
Sent: Tuesday, August 14, 2001 1:23 AM
To: Harrell, Tim; suse-linux-e@suse.com
Subject: Re: [SLE] AMD running too hot
Tim --
I'm certainly not an expert on cooling systems, but I did 
some reading a
while back that pursuaded me to think that a front fan + a rear fan
(configured front=intake; rear=output) were operating in 
series and would
move more air thru the box than two fans in parallel (i.e., 
both intake, or
both exhaust).  I doubt if this rule is absolute ==> for 
example, if the
resistance of air moving through the box were zero, running 
them in parallel
would move the same volume of air.  However, this theory that 
I read about
seems to have something to do with the fact that resistance 
to airflow is
nonlinear with respect to volume (e.g., something like: 
resistance increases
as a function of velocity squared).  So, by analogy, fans in 
parallel would
be fighting each other, whereas in series they would provide 
the greater
pressure appropriate to the greater volume.
I just was wondering how this fit with your suggestion to 
"forget the front
case fan" and "fit it to the rear instead".  Maybe you're 
right: - -  on my
computer the front mounting bracket allows a lot of air FROM 
INDSIDE the box
to come into the intake. But, on the other hand, with a 
baffle restricting
internal air getting to the intake side of the front fan, it 
would seem to
increase the pressure differential and move the greatest 
volume of cooling
air thru the box. ( I realize that this neglects the CPU fan 
-- but, isn't
this something that exchanges heat between the CPU and the 
internal air
which is in transit to the exhaust?)
What's really going on here?? Does anyone have a good explanation?
Peter Hollings
----- Original Message -----
From: Harrell, Tim 
To: 
Sent: Monday, August 13, 2001 8:28 AM
Subject: RE: [SLE] AMD running too hot
That setup is v. similar to mine - I have a 1.33 G Tbird also and a
Thermosonic heatsink. The OC guys tend not to go for ThermalTakes
because, although quiet and reasonably efficient, they're not the most
effective coolers around. Even so you should not be getting temps as
high as that unless you've overclocked it. I take it you're running a
standard 1.33 Ghz set at 10x with a 133MHz bus.
First advice is to forget about the front case fan and fit it to the
rear instead. Front fans are often next to useless as they can just
recirculate hot air over the board. Check the cooling guide on AMD's
site for more information. Check you have an AMD approved PSU (ie not
front-venting). Fitting the exhaust fan will help lower your 
system temp
but to keep your core temp low you need to ensure you either have a
decent thermal interface between the heatsink and the AMD core (like
Arctic Silver II).
I get an idle temp of 45C. I'm not sure what the full load 
temp is as I
don't have a reliable way of finding out the temperatures in 
Linux. I've
tried the sensors package but even after configuration that 
gives crazy
temperatures like 50C for the system temps on idle (I know 
from the BIOS
that it's around 35C).
As a matter of interest, what ways are you (or others reading this)
determining your temperatures?
Tim Harrell
...
-----Original Message-----
From: Guy Van Sanden [mailto:sienix@crosswinds.net]
Sent: Monday, August 13, 2001 2:46 PM
To: suse-linux-e@suse.com
Subject: [SLE] AMD running too hot
Hello
I've been working on this for a long time now (and posted it
previousely), but I
can't seem to find any answers, other than that I'm not the
only one with the
problem...
I own an Athlon 1.333 Ghz an I'm running Linux.
My CPU is running too warm, 56 °C and up...
When I run something CPU-intensive, for a long time (like MP3
ripping), I can
see the CPU temperature rise, and at about 60°C, my system
automatically
reboots :-(
So, I have this really beautiful machine here... but if I
really try to use it,
it goes down :-(
The frustrating part is that it's working fine with windows (I
installed it to
check thid problem)...  It's running at 47°C idle, and gets to
58°C under
highest stress.
Anyone got any clue what's causing this... It's like the CPU
is ignoring the HLT
instruction when idle...
SuSE Linux 7.2 running kernel 2.4.4
AMD AThlon 1.333 GHZ
ThermalTake Volcano II cooler (running 5000 rpm)
Extra cooler intake (front-bottom of my case @ 2500 rpm)
Asus A7V133 Mb.
256 MB SDRAM
Help, It's making me desperate...
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