3 Replies Latest reply on Jan 25, 2017 6:36 PM by mseszeny

    Xeon memory bandwidth

    tptacek

      Hi,

       

      I'm trying to understand the maximum (theoretical) memory bandwidth of Xeon processors so that our applications can maximize their bandwidth.  I thought I had it figured out, but now I have a processor where I don't understand how the maximum numbers make sense.

       

       

      Here's an example I think I understand:  Xeon E5-2630 v3 (Haswell-EP).  The maximum memory bandwidth (according to ARK) is 59 GB/s.  It has 4 memory channels and supports up to DDR4-1866 DIMMs.  The peak transfer rate of a DDR4-1866 DIMM is 14933 MB/s, and 14933 * 4 = 59732 MB/s, so this adds up.

       

       

      What I don't understand: Xeon E7-4830 v3 (Haswell-EX).  The maximum memory bandwidth is 102 GB/s.  But it also supports up to DDR4-1866 and has 4 memory channels!  So how does it get 102 GB/s?  One theory is that the E7-4830 v3 has two memory controllers.  While cpu-world confirms this, it also says that each controller has 2 memory channels, so it still doesn't add up.

       

       

      I'd appreciate any help from the experts over here.  Is the number of memory controllers documented by Intel anywhere?  I couldn't find it.

       

       

      Thanks in advance!