[Beowulf] materials for air shroud?

mathog mathog at caltech.edu
Fri Sep 16 10:52:04 PDT 2011


Now that I have seen the problem for two sockets, it made me wonder 
what
the manufacturers did for 4 socket motherboard designs.  Easy enough to 
find out.
A Google Image search for:

    "quad socket" motherboard

shows:  some took air flow into account, and some didn't.

There are quad socket motherboards with the sockets in rectangular 
arrangements, so that
air cooling all of those equally in a 1U or 2U case is going to be 
really hard, and probably
it just isn't done.  Water cooling would work, or in a 3U or 4U air 
cooling by snaking in
ducts, but either way it would be a PITA.

Then there are other motherboards where air flow was clearly taken into 
account, and the sockets
are lined up so that they are not in each other's air flow.  Or at 
least not much.  This one
there might be a tiny bit of overlap right at the edge of the  heat 
sinks:

    
http://www.tyan.com/product_SKU_spec.aspx?ProductType=MB&pid=670&SKU=600000180

That would be easy enough to handle by redirecting the hot air
a few millimeters to the side with a small plastic "wall".

In other designs they line the sockets up straight across the board, so 
that
there is no way for one CPU to "breathe" the hot air from another:

   
http://www.zdnet.co.uk/reviews/sme-servers/2010/06/25/dell-poweredge-r810-40089356/

That Poweredge case looked pretty long, so I checked the specs and it 
was 72 cm, which was
7 cm longer than the longest 2U case in any of my racks.  (And only 2 
cm longer than some
old dead dual motherboard 1U cases from Racksaver that have not yet 
gone to recycling.
Yes, those really had two motherboards in them, one behind the other.) 
Being Dell they
may have gone with a nonstandard motherboard form factor.  Standards 
are for the little guys!

At the other end of the spectrum, in the "what were they thinking?" 
category, there are
2 socket designs like this one (where the manufacturer only recommends 
a 4U case, with
active heatsinks):

   
http://www.supermicro.com/Aplus/motherboard/Opteron4100/SR56x0/H8DCL-6.cfm

This definitely points up one advantage of more cores/socket - it is 
easier to cool
all the cores equally if there are fewer sockets.  There is also the 
blade approach,
but that is a whole different ballgame in terms of price versus the 
more generic rack servers.

Regards,

David Mathog
mathog at caltech.edu
Manager, Sequence Analysis Facility, Biology Division, Caltech


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