Hi. I have an AMD 64 bit, 6-core processor (fairly new). I run windows 7, and my question involves multiple runnings of a chemistry SIMULATION program that I have -- the calculations for one model takes hours. I am wondering how the speed of the calculations would be affected by running, say, 4 simulations (on 4 DIFFERENT models) at one TIME. If I have a multi-core processor, does that mean that I can run multiple simulations with ease? If I have a 6 core processor, can I run 6 jobs at once, with no change in the processing time (as compared to just one job running)?

Thanks!

This really depends on how the program is written

If it written to only take advantage of one core, than yes, simply run 6 instances of the program, then set the affinity of each of the processes to one core only.

The best way to tell is to run one copy of the program, then fire up task manager (ctrl + shift + esc)
Navigate to the performance tab to see the usage of your cores.
start the simulation and note which cores are now in use while the operation is taking place.
If only one core shoots up, then GREAT
If it is utilizing 2 cores, or more to do its processing, then you will be limited to running the amount of processes divisible by that number eg if using 3 cores, than you could only run 2 without any performance loss.

To change affinity:

navigate to processes tab, locate the process in the list. This may be simplified by clicking the 'name' field sort once, for descending alphabetical order.

Once found, right click, set affinity.

Untick the cores you do not wish the process to have cpu cycles on. click OK

Tada

btw If the process is only using one core, you are then technically wasting 5/6ths of your CPU's potential :O