[gmx-users] (no subject)

Mikko Huhtala mhuhtala at urquell.abo.fi
Mon Mar 25 09:53:42 CET 2002

From: Mikko Huhtala <mhuhtala at abo.fi>
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Message-ID: <15518.58774.255086.490557 at urquell.abo.fi>
Date: Mon, 25 Mar 2002 10:53:42 +0200
To: gmx-users at gromacs.org
Subject: Re: [gmx-users] pentium III vs Pentium IVs
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	<3C9EDB9C.36D74E20 at gwdg.de>
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Bert de Groot writes:
 > David van der Spoel wrote:
 > > 
 > > On Sun, 24 Mar 2002, Erik Lindahl wrote:
 > > 
 > > >The only reason to go with Pentium4 is if you need double-precision in
 > > >your MD calculations.
 > > Or if you do something else, besides MD, that uses a lot of double
 > > precision floating point. Benchmarks of Gaussian (quantum chemistry) show
 > > that the fastest P4 is quite a bit faster than the fastest Athlon.
 > > 
 > Another issue to consider is the air conditioning in your computer room.
 > Those Athlons produce quite a bit of heat in comparison to intel CPU's.
 > We had to install a much more powerful airco after our 12 dual athlons
 > had arrived. 

Our 8-node Pentium 4 cluster is not exactly running cold either... no
need for new air contidioning though.

Has anyone tried compiling Gromacs with Intel's C/C++ compiler? The
compiler is free of cost for unsupported academic use and it makes
quite a drastic difference compared to GCC on Pentium 4. I haven't
tried recompiling Gromacs, but with a few other floating point
intensive software packages we have seen over 30 % performance
increases compared to GCC binaries. Apparently you can get quite good
performace with GCC and Athlons, too, by being careful with compiler

One disadvantage about Pentium 4 is (or at least has been) that not
many people have them and hence some bugs that show up only on P4 do
not get fixed very quickly. We have had some random problems with
Mosix as well as some binary-only packages (that have nothing to with
MD). Anyways, this should not be an issue if P4 becomes more common.


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