I'm not new to Linux but I'm not an expert either, so bear with me if this is a stupid question.

We're running Ubuntu 14.04.2 from a live session USB to test out a new dual CPU workstation. It has two Intel Xeon E5-2650V3 processors, which are ten-cores with hyperthreading, so I should be seeing 40 CPU's in System monitor. For some reason I am only seeing 32 CPU cores. Is there a limit to how many Ubuntu can recognize?

I'd only be seeing 20 CPU's if one of the processors wasn't installed correctly, so I doubt this is a hardware problem. Under "About this computer" I am seeing "Intel Xeon(tm) E5-2650 V3 Processor (2.3 GHz) x 16"

Here is the output of lscpu: enter image description here

  • 3
    Open a terminal and run lscpu and add the results to the question – Mark Kirby Jun 14 '15 at 19:49
  • Hyperthreading generally adds very little anyway, so I recommend turning it off in the bios. – psusi Jun 15 '15 at 0:16
  • 1
    Done, but stack exchange made the image super small. It shows 40 CPU's here, but 32 in System monitor and About this computer. – Derek Jun 15 '15 at 20:30
  • Just copy paste the text, select it and press Ctrl-K to format it. Please don't post pictures of text. – muru Jun 15 '15 at 20:33
  • The system in question has no internet access, but I installed RHEL 7.1 and it recognizes every core. – Derek Jun 21 '15 at 20:37

This have been reported as bug in Ubuntu 13.10 :


It affected only 2 people, therefore the fix never maked it into production version. I am suspicious that it was never fixed afterwards, so it is still in 14.04.2.

I think, you can dowload the fix for yourself and compile your own version of libgtop2 if you mind.

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