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FX-8120 showing as 4-core

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  • FX-8120 showing as 4-core

    I have run a benchmark using PT 8 and for my system it says the it is 1 processor with four cores. I have looked on the forum and didnt see anything, also on some baselines they show up as 8-core and others it shows 4-core. Any ideas

  • #2
    yea my 8350 is doing the same thing


    • #3
      I had a look through the ~400 baselines we have collected for the 8120 and 8350 and didn't find a single example of either of these CPUs reporting 4 cores.

      What are the baseline numbers that you are referring to?

      We have seen two instances of this in the past. The first one was only seen (to date) with i7 CPUs with hyperthreading. It can happen if you have upgraded from a 2 or 4 core CPU to a 8 core CPU. Windows doesn't always notice the upgrade. See this post for details and a solution.

      The second instance was bad settings in BIOS for the "Max CPUID Value Limit" setting. See this post for details and a solution.


      • #4
        When you look at the baseline it shows 8 core it is when you look at the system tab in PT8. I have a picture of what I am talking about the first is mine the other 2 at the same CPU


        • #5
          Also I have checked the limit cpuid setting in bios and it is disabled.


          • #6
            On further investigation it turns out our database structure was hiding the core count for individual baselines (it was reporting the generic core count for that CPU type).

            So yes, it seems like there is a problem. It doesn't seem to impact the benchmark results as we are running 8 test threads even though only 4 cores are being reported.

            We have been trying today to determine if there is some common factor that is causing the issue on some machines (e.g. 32bit systems only), but didn't find any common factor as yet. We'll keep looking into it tomorrow.


            • #7
              NO mine is 64 bit


              • #8
                As mentioned, we didn't find any common factor among the machines with the problem as yet. We looked a lots of things, motherboard type, 32/64bit, BIOS version, overclocking, etc.

                We have a FX-8150 in house, but of course our example machine doesn't exhibit the problem.

                Would be good if you could send in a debug log file. See,


                • #9
                  OK, we think we have gotten to the bottom of it.

                  We were using a function in Windows called getlogicalprocessorinformationex to get the core count. Details are here,

                  It seems that Microsoft changed the behaviour of this function in all Windows 8 releases, plus also made a patch available for Win7. This patch has been applied by many Win7 users, but not all. The patch is not available for Vista nor XP.

                  Details of the patch are here,

                  Before the patch is applied, the AMD FX Bulldozer CPUs would report 8 physical CPUs and 1 logical CPU per core. After the patch is applied these AMD chips would report 4 physical CPUs and 2 logical CPUs per core. The same issue effects some if the newer Opteron chips.

                  So Vista and XP always report 8 cores. Win8 always reports 4 cores and Win7 might report either 4 or 8 depending on the patch.

                  The post patch situation is a more accurate reflection of the real situation as the 8 cores in these CPUs are not full cores (AMD calls them 'modules' in some of their marketing). There are really 4 full cores in the CPU, but each of the 4 cores has some duplicated hardware that allows 2 threads to run. Details are here,

                  Fortunately this is just a display issue and doesn't impact on the benchmark results.

                  What we will be doing either today or tomorrow is putting out a patch to make this situation more obvious in the user interface, by adding a field to display the logical core count as well as the physical count. (this is somewhat similar to the Intel Hyperthreading feature).


                  • #10
                    Ok thank you for your work!!!!