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Old   January 25, 2010, 12:51
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Fatema Zandi Goharrizi
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Hi
would any one help me with using full capacity of an i7 system on cfx runs.
actually I use a system with an intel i7 920 cpu and 8 GB RAM and have cfx 11
but I just can use 4 cores on my runs and it gives errors due to licence if I'm right.
thanks
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Old   January 26, 2010, 03:52
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I assume Ansys CFX has the same license configuration as the Mechanical modules. In that case the number of cpu's is limited at 2 for one license. If you want to use 4 cpu's you should buy a second license.
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Old   January 26, 2010, 11:29
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Fatema Zandi Goharrizi
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Hi
thank you
I can get run with 4 core but not 8
would you please tell me if I have buy license for 8 or for 4 to run with 8 core of an i7
thanks again
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Old   January 26, 2010, 17:34
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You will need to buy additional licenses to run 8 processes. But don't bother. The I7 chip has 4 cores so running any more processes on it is bad. It looks like 8 processes on task manager as each core looks like 2 cores due to hyperthreading - but CFX does not take advantage of hyperthreading so you do not gain a useful speedup by using 8 cores.

Unless you have a dual CPU system, then you do have 8 cores. Then you just need to get that many licenses to run it.
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Old   January 27, 2010, 05:56
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Quote:
Originally Posted by ghorrocks View Post
You will need to buy additional licenses to run 8 processes. But don't bother. The I7 chip has 4 cores so running any more processes on it is bad. It looks like 8 processes on task manager as each core looks like 2 cores due to hyperthreading - but CFX does not take advantage of hyperthreading so you do not gain a useful speedup by using 8 cores.

Unless you have a dual CPU system, then you do have 8 cores. Then you just need to get that many licenses to run it.
I appreciate your useful helps
Would you please say how I can understand that a system is dual cpu system or not?
What do you mean by many licenses exactly?
Thank you
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Old   January 27, 2010, 16:51
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Did you get a computer with 1 CPU or 2? If you can't answer this then open the box and have a look!

Parallel licenses are per-process. You need 8 to run an 8-way parallel job but only 4 to run a 4 way parallel job.
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Old   January 28, 2010, 03:49
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Quote:
Originally Posted by ghorrocks View Post
Did you get a computer with 1 CPU or 2? If you can't answer this then open the box and have a look!

Parallel licenses are per-process. You need 8 to run an 8-way parallel job but only 4 to run a 4 way parallel job.

thanks a lot friend
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Old   June 4, 2010, 11:01
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I guess hyper threading may help....very little bit of CFD formance. It won't worth the price of licensing for the extra 4 virtual cores and just get less than 20% improvement.


Take a look this:
http://techreport.com/articles.x/18581/14
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Old   June 5, 2010, 05:31
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CFX has not been complied to use hyperthreading. Don't use it. Just leave the virtual cores sit idle or even better disable them in the BIOS.
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