Thermal Problems

Ken Light klight at
Thu Jul 24 16:16:54 EDT 2003

I think there are a lot of compromises in this layout.  The centrifugal
blower in the back looks like it is helping mostly the power supply, not the
CPUs.  The CPU fans doesn't look like they are being very effective when the
top of the case goes on and the little muffin fans near the memory are
notoriously inefficient when you present them with any kind of flow
restriction like that duct.  I would be tempted to experiment with different
CPU heat sinks and a bigger blower on front to move air over them.  The
following links show some views of a pretty good Xeon setup.  Maybe you can
get some ideas of things to try (by the way, the CPUs are under the paper).
The case is custom from Microway Inc. and is pretty deep, but the extra
space makes for a good layout.  Good luck.


> -----Original Message-----
> From: Michael T. Prinkey [mailto:mprinkey at] 
> Sent: Thursday, July 24, 2003 9:33 AM
> To: Mitchel Kagawa
> Cc: beowulf at
> Subject: Re: Thermal Problems
> On Wed, 23 Jul 2003, Mitchel Kagawa wrote:
> > Here are a few pictures of the culprite.  Any suggestions 
> on how to fix it
> > other than buying a whole new case would be appreciated
> >
> >
> >
> > 
> > You can also see how many I'm down... it should read 65 
> nodes (64 + 1 head
> > node)
> >
> > 
> > Mitchel Kagawa
> > Systems Administrator
> > 
> The Intel Xeon ships with an interesting heat sink/fan/shroud 
> system.  
> For an normal case, you can mount the fan on the top of the 
> shroud which
> makes it work much like a "normal" heat sink/fan...the air 
> comes in the
> top and blows down onto the CPU.  But, for low-profile 
> installations (mine
> were 2U), the fan attaches to the side of the shroud to form a "wind
> tunnel."  Maybe a similar solution would exist in your case, 
> i.e., taller
> heat sinks (~1") with one or two fans mounted on the side 
> blowing across
> the heat sink.  I did a quick search online, but couldn't 
> find a vendor 
> for this type heat sink.  Sorry.
> You might be able to experiment.  Fans are usually only held 
> in place with
> oversized screws that go easily into soft heat sinks.  You 
> can probably
> build a pair of test heat sinks in 10 minutues.  The flow from the fan
> should be aligned with the fins.  Depending on the type of 
> heatsink you
> start with, you might be able to direct the output flow in 
> any direction
> you choose.  From the photos, I would recommend that you 
> place the fans on
> the side of the heat sink near the front of the case so the exhaust is
> directed to the vents at the rear of the case.
> Good luck,
> Mike Prinkey
> Aeolus Research, Inc.
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