[Wien] help on computer for WIEN2k calculation

[Michael Gurnett]

We have a system with the intel dual core 820. Based on the price and the
obtained benchmarks I would say this is a very good system. One of the
problems however with the intel dual cores at the moment is that they run
very hot, and the boxed cooling which comes with the processor is not
really sufficient. So it is recommended that you buy a better fan for the
processor. The speed of the processor is very inpressive. The price for
the 830 and 840 is much higher and for the speed increase over the 820 may
be questionable whether it is warranted. As Peter mentioned, Intel will be
releasing an improved dual core sometime in the not to distant future
(according to rumours on the net), and with any luck these may run cooler.
I myself have been toying with overclocking the 820 and have obtained some
very good times (second fastest on the benchmark page). With the dual core
processors you do need alot of ram if you want to use both cores to their
fullest, so you need to buy a motherboard that supports atleast 4 Gb.

Michael

-----Original Message-----
From: Peter Blaha <pblaha at theochem.tuwien.ac.at>
To: A Mailing list for WIEN2k users <wien at zeus.theochem.tuwien.ac.at>
Date: Tue, 20 Dec 2005 11:52:45 +0100 (CET)
Subject: Re: [Wien] help on computer for WIEN2k calculation

> Hi,
> The answer to your question is not so simple and depends a lot on:
> 
> is this dedicated to WIEN2k or will other software also have a large
> fraction of cpu time ?
> how much money do you have in total (there's a big difference between
> 5000 and 100000 or more $) ?
> For which WIEN2k tasks do you plan (system size) ?
> 
> For many tasks AMD and Intel cpus are fairly "equal", i.e. they perform
> similar within 10-20 % and either one may be faster for a particular
> case.
> 
> For WIEN2k this is quite different ! Due to the dominant time of 
> diagonalization and the high efficiency of Intel cpus for this task,
> an Intel cpu is significantly faster than AMD (160 vs 260 seconds, see 
> benchmarks) !!
> 
> dual core is now the way to go (very cheap (almost) doubling of
> performance),
> support by BLAS-libraries, similar for AMD and Intel.
> 
> 
> for "regular" WIEN2k cases (system size usually below 50 atoms; maximum
> of
> 100 atoms/unit cell) and a "limited" budget (a few k$):
> 
> I'd go for a couple of Intel P4 D-830 or 840 with Gbit-network and SATA
> disks.
> 
> I'd use Xeons only for really "big" machines (and more money).
> Furthermore
> at the moment the dual-core Xeons run only at 2.8GHzt, but
> new processors (with 65 nm technology) are expected soon, so I'd almost
> "wait" (if possible).
> 
> I'd use AMD only for even bigger machines and big "cases". In these
> cases
> you may want to use the mpi-parallel version and thus you need a fast
> network 
> (Infiniband), which is quite expensive. In this case (and ONLY in this
> case)
> it pays off to buy these multi-cpu machines (like like a two or four
> socket -
> dual-core AMD Opteron).
> 
> 
> memory: again it depends on the cases you want to study. Minimum is 2
> GB,
> when you plan for bigger cases, buy 4 GB per "socket".
> 
> Regards
> 
> > Dear users,
> >     We are planning to buy a new computer for WIEN2K calculation. 
> Three
> > kinds of CPU, AMD Athlon 64 X2 3800+(dual core), Pentium D 830(dual
> core) or
> > double Xeon 2.8G are considered . But we are not sure which one is
> better
> > for WIEN2K. It seems that Intel CPU is better from the benchmark on
> the
> > WIEN2k website. Does dual-core CPU is better than double CPU(one
> core)?
> >  We greatly appreciate that somebody can give us some suggestions
> about
> > CPU,memory and so on.
> > 
> > Best regards.
> > 
> > Zeming
> > 
> 
> 
>                                       P.Blaha
> -----------------------------------------------------------------------
> ---
> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
> Phone: +43-1-58801-15671             FAX: +43-1-58801-15698
> Email: blaha at theochem.tuwien.ac.at    WWW:
> http://info.tuwien.ac.at/theochem/
> -----------------------------------------------------------------------
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