3 Replies Latest reply on Aug 16, 2017 4:26 PM by Intel Corporation

    Why E5-2697v4 can not exceed 2.8GHz, no matter how many cores are in full load?


      Now I use it as Linux PC, and this problem does confuse me for a while.


      It's confirmed that its max turbo boost frequency follows the number of cores enabled in BIOS, but not the number of full load cores.

      Therefore even I can read Linux reporting this CPU's max frequency is 3.6GHz, it works only when 1 or 2 cores are enabled in BIOS, just like the turbo boost ratio table mentioned in the official datasheet.


      I've dumped some MSRs for turbo boost ratio control, but found nothing incorrect.

      Also I asked motherboard vendor whether they can handle it, but their customer service only replied that this motherboard tends to install Windows but not Linux.


      Is there any way to fix it like changing some BIOS settings, or modifying some related MSRs on Linux?


      p.s. It only works normally on Linux-4.8 with the original BIOS, and failed on the newer Linux kernel & BIOS.