CCL:G: Gaussian on a PC computer

 Sent to CCL by: "Gkourmpis, Thomas"
 [Thomas.Gkourmpis{:}borealisgroup.com]
 Hello
 According to my chats with the guys in Gaussian the Windows version (what they
 call multicore) is a 32bit version so is able to use up to 2GB of RAM. The issue
 with using all the cores in a computer is in essence a matter of how much RAM
 can the program access, since Gaussian is using a system where the program
 itself decides how many processors will use. In principle it can use up to 4 but
 since you're limited by your RAM allocation most times it will use anything
 between 1 and 3. Also don't forget that the 2GB are total memory, so they're
 shared between the cores. Therefore in calculations that need a lot of memory
 like SCFs or frequency you're better off using one or two cores instead of four
 (the program will do that for you).
 In all if you want to get top performance from Gaussian either get the Linux
 version or pressure them to finish up and release the 64bit version for Windows
 :-)
 I hope this helps
 Thomas
 -----Original Message-----
 > From: owner-chemistry+thomas.gkourmpis==borealisgroup.com=ccl.net [mailto:owner-chemistry+thomas.gkourmpis==borealisgroup.com=ccl.net] On
 Behalf Of willsd{:}appstate.edu
 Sent: Friday, February 17, 2012 2:10 AM
 To: Gkourmpis, Thomas
 Subject: CCL:G: Gaussian on a PC computer
 Sent to CCL by: [willsd(a)appstate.edu]
 While I am not sure about the windows version, the 64-bit (intel) linux version
 of G09 I use at my university will
 certainly use all 8 cores I have on a shared memory node.  I think you must use
 the linda parallel version to run
 jobs on multiple compute nodes, but I think the normal version requires nothing
 special to run on shared cores
 using the same memory space.
 Steve Williams
 ----- Original Message -----
 > From: "Ronald Cook cookrl(-)tda.com" <owner-chemistry()
 ccl.net>
 Date: Thursday, February 16, 2012 7:16 pm
 Subject: CCL:G: Gaussian on a PC computer
 To: "Williams, Steve " <willsd() conrad.appstate.edu>
 > Hi Rapha
 >
 > I have been running G09W calculations on a Windows XP system using
 > an Intel
 > i7-2700K processor.  The chip is normally clocked at 3.5GHz, but we
 > havebeen running calculations for several months now with the system
 > overclocked at 5GHz with no overheating problems.  We see about 30%
 > decrease in computational time.  Furthermore, G09W does not use
 > hyperthreading.  So If you go into the task manager and select
 > processesand right click on G0W9 and then uncheck processors 4-7
 > (which are virtual
 > anyway) and just use processors 0-3 you can get an additional 30%
 > decreasein computational time.
 >
 > Ron
 >
 > On Thu, Feb 16, 2012 at 2:53 PM, Raphael Martinez
 > raphaelmartinez1983++gmail.com <owner-chemistry++ccl.net> wrote:
 >
 > >
 > > Sent to CCL by: "Raphael  Martinez" [raphaelmartinez1983:-
 > :gmail.com]> Hi everyone:
 > > If I have an Intel quad core, 16GB ram computer with either linux or
 > > Windows, does it Gaussian uses all 4 cores if I request to do so
 > in the
 > > input file?
 > > If not, what would be the best processor to have in a personal
 > computer to
 > > run Gaussian?
 > > Thanks
 > > RaphaI>
 > >
 > >
 >
 >
 > --
 > Ronald L Cook
 > Principal Scientist
 > TDA Research, Inc.
 > cookrl++tda.com
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