1 Reply Latest reply on Oct 2, 2018 10:20 AM by misterj

    Slow render speed only on AMD CPUs , why that happens ?

    valdo_d

      Hello !

       

      I have my hands on new CPU week ago feed my scene and tested 2990wx with renderman and it's deadly slow .

      numbers are just terrifying .. average Intel CPU just easily outperforms 32 cores 

       

      I'm looking all over the internet and it seems that memory bandwidth is an issue , I'm not sure but most likely it's how AMDs new CPU treats and lets data from memory to flow into CPU

      thank god I didn't buy that CPU for rendernode month ago and decided to make some research .

       

      So , let's do some math !

       

      1) Take a look at that topic here :

      https://www.pcworld.com/article/3298859/components-processors/how-memory-bandwidth-is-killing-amds-32-core-threadripper-performance.html

       

      2) I took that from renderman forum , it requires registration access so I saved it to PDF and attached here , it's addressing same issue I'm talking about .

       

      frankly had my eyes also on epyc CPUs , and also hope on upcoming AMD Rome , but if it will continue like that I don't know .  

      when someone buys 10k$ dual socket PC he can expects to multiply render speed by factor of 5-10x compared to average cpu

       

      when you're advertising your products and doing that Cinebench 15  tests , they are small , all bench scenes are small , and it flies from RAM to CPU just like in fraction of second but when you're doing (rendering)  heavy content , then it bottlenecks the whole calculation .

       

      Is that really AMDs way to handle memory bandwidth ?

       

      Will Rome CPUs have same issues ? because if it will it means in heavy rendering 2 or 3 average intel CPUs  will outperform 2 dual socket Rome 

       

      I was thinking how to ask long in short, and only this comes to my head

       

      What is going on ?

        • Re: Slow render speed only on AMD CPUs , why that happens ?
          misterj

          valdo_d, I would like to point out that this is a user forum.  You are not contacting AMD and I, and most here, do not work for AMD.  To contact AMD please open an Online Support request.   There are a number of posts here about this very problem and I suggest you do some research.  The 2990WX, in particular, seems to have an OS scheduler problem, but I cannot tell what OS, or memory, or power supply, etc....you have.  If you want some help, please post the detailed specifications of the system you are using that you are glad not to own.  If I give you my address will you send it to me?  Please watch this video.  I have no knowledge of Rome CPUs - please ask AMD.  Level1Techs Forums is a great forum.  Enjoy, John.