Better CPU

uri
uri Altair Community Member
edited October 2020 in Community Q&A

Which CPU will work faster?

i7-7800X @ 3.5GHz (6 cores) 

i9 10900 @2.8 GHz (10 cores) 

 

 

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Answers

  • Adriano_Koga
    Adriano_Koga
    Altair Employee
    edited August 2020

    I believe that there's many factors influencing that question. Memory probably will have a key role as well.

     

    Also licensing. Depending on your license it won't matter having more core's. 1-4 is one count in general. 5-8 is another..and 8-16 another.

     

    Regarding the cpu's i'd guess the newer generation 10th family performs better, but again, processor only doesn't mean anything.

  • ydigit
    ydigit
    Altair Employee
    edited August 2020

    As Inspire Cast scaling is good for 4 cores, I would go for the the i7 with more frequency. As those 10 cores of i9 are unlikely to bring great benefit for Inspire Cast. Unless you want to run two jobs with 4 cores each. 

  • QuyNguyenDai
    QuyNguyenDai Altair Community Member
    edited August 2020
    Altair Forum User said:

    Which CPU will work faster?

    i7-7800X @ 3.5GHz (6 cores) 

    i9 10900 @2.8 GHz (10 cores) 

     

    It doesn't make sense if you just look at the frequency and the number of cores.

    Another factors to check: cache, supported memory type,...

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited August 2020

    At first shot i9 looks better, specially if a good cooling system is used.

     

    Even if the original name looks like i7 specs has a higher clock, when you look into the details i9 specs might have a higher clock frequency if certain temperature thresholds are satisfed (and should be easier as it has less than 1/2 TDP).

     

    What makes me doubt is the memory bandwith, as the i7 has 4 channels (but at inferior speed) and i9 has 2 channels, and it is known that memory bandwith has plays a major role in CFD type simylations.  I would say i9 is better, but I would not bet all my money on it.

     

    This does not take into consideration the processor cost at all.

  • SouravDas0306
    SouravDas0306
    Altair Employee
    edited August 2020
    i9 with 10 cores, and upto 6 cores the speed will increase, beyond 6 cores, the speed will remain same
  • uri
    uri Altair Community Member
    edited August 2020

    Now I am confused...

    Dear Sourav, You say I9 is better, but no need for the 10 cores as it is 'using' 6 only?

    Are there recommendations by Altair?

     

     

  • SouravDas0306
    SouravDas0306
    Altair Employee
    edited August 2020

    Hi Uri,

     

    We did some study,it uses max core as it is available in the machine, but it default we set it for 4 cores, performance will increases up to 6 cores, and I guess beyond it remain same.
     
    Regards
    Sourav  
  • QuyNguyenDai
    QuyNguyenDai Altair Community Member
    edited August 2020

    What do you mean '... beyond it remain same'?

  • Adriano_Koga
    Adriano_Koga
    Altair Employee
    edited August 2020

    I believe he means above 4 core's no considerable performance increase was found..just like convergence study.

    So for this application don't waste resources as it will not leverage more tham 4 core's.

  • QuyNguyenDai
    QuyNguyenDai Altair Community Member
    edited August 2020

    If you does not found any advantage about CPU time above 4 cores, your model is NOT BIG enough for real parallel computing.

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