[Wien] Hardware (i7-7700k?) for WIEN2k

[Gavin Abo]

Some additional comments:

If you need an idea of about how computational intensive a WIEN2k 
calculation might be for around 60 atoms per cell or more.  The links 
below and links in those posts might be helpful:

https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg14035.html
https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg01420.html
https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg05784.html

The hardware specifications for the i7-7700K and E5-2623 v3 processors 
should be at the links:

https://ark.intel.com/products/97129/Intel-Core-i7-7700K-Processor-8M-Cache-up-to-4_50-GHz
http://ark.intel.com/products/83354/Intel-Xeon-Processor-E5-2623-v3-10M-Cache-3_00-GHz

The specifications look fairly similar.  So maybe there would not be too 
much of a difference in the WIEN2k calculation run times between the two.

The i7-7700K supports a Max Memory Size of 64 GB.  The E5-2623 v3 could 
have a major advantage when it comes to supporting a Max Memory Size of 
768 GB.  However, if the motherboard the E5-2623 v3 goes on does not 
have memory expansion slots for more than 64 GB or if you never plan to 
add additional memory modules to increase the memory beyond 64 GB, then 
that would not matter.

The i7-7700K does have about a 1 GHz faster processor frequency and it 
looks like it supports a faster RAM (DDR4-2133/2400, while the E5-2623 
v3 supports a slower DDR4 with frequency of 1600 or 1866 MHz).  So this 
might give it better performance than the i7-7700K if the calculation 
uses less than 64 GB of RAM.  Above 64 GB, the workstation would likely 
use virtual memory and disk caching may significantly slow a calculation 
(whereas the E5-2623 v3 with more than 64 GB should extend the limit of 
this RAM bottleneck).  The i7-7700K also supports DDR3L-1333/1600.  If 
both the i7-7700K and E5-2623 v3 workstations happen to use the same 
DDR3 1600 RAM, then no speed up or slow down is expected from the RAM 
frequency.

More importantly than all that may be the launch date for the E5-2623 v3 
of Q3'14, while Q1'17 for the i7-7700K.  The Xeon E5-2623 v3 has been 
around awhile.  So Linux distributions most likely have drivers that 
support this processor.  With the i7-7700K being so new, you might have 
to be more cautious.  If you decide to get the i7-7700K, I recommend 
checking that the Linux distribution, compiler (in particular if you 
plan to use a non-Intel compiler like gfortran), and libraries (such as 
a blas library with the non-Intel compiler) that you will be using are 
able to support and recognize the processor.

As an example, I think it was the Intel HD Graphics 530 onboard the 
Intel Skylake processors when they were first launched that didn't have 
a good Linux driver [ 
https://askubuntu.com/questions/698168/cant-get-intel-hd-graphics-530-skylake-i7-6700-to-work 
]. If I recall correctly, the graphics were broken (or of poor quality) 
for several months until the drivers were finally released.

Of note, there is also seems to be a E5-2623 v4:

http://ark.intel.com/products/92980/Intel-Xeon-Processor-E5-2623-v4-10M-Cache-2_60-GHz

On 9/18/2017 6:54 PM, Yundi Quan wrote:
> hi,
>
> 4 cores with 8 threads is probably OK for using WIEN2k to study 
> transition metal oxides. For post-processing tools, such as 
> wien2wannier, it requires more memory. But 64 GB is enough in most 
> cases. I once bought a Dell XPS with 4 cores and 8 threads, 16 GB 
> memory back in 2011. It worked well for most of my calculations. Hope 
> this helps.
>
>
>
>
> On Mon, Sep 18, 2017 at 2:44 PM, Karsten Küpper <kkuepper at uos.de 
> <mailto:kkuepper at uos.de>> wrote:
>
>     Dear WIEN2k-community,
>
>     We want to buy a workstation dedicated to run WIEN2k.
>     Our aim is to calculate mostly transition metal oxides with unit
>     cells ranging from 24 - 128 atoms supercells.
>     We are thinking about a workstation with at least 4 cores, at
>     least 64 GB RAM, and a 1TB SSD as a starting point.
>
>     1) May that be a reasonable choice?
>
>     2) Has anybody experiences with the i7-7700K 4.2 GHz (maybe also
>     compared to Intel-Xeon E5-2623 processors),  as there is no
>     benchmark test available on the WIEN2k homepage by now.
>
>     Thanks for your efforts in advance!
>
>     Kind regards
>     Karsten Küpper
>
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