Bios not detecting Second CPU in Dual E5410 setup

Posted on 2011-10-26
Last Modified: 2012-05-12
I have a server that i recently checked and could only see 4 cores in Device Manager. It is running ok
The server was rebooted and the Bios reports same, i.e only 1 cpu enabled. For the life of me i cannot find how to enable the second CPU if indeed there is such a setting, jumper. I have searched high and low for a fix, Any suggestions???

SuperMicro Motherboard X7DVL-E, Dual Intel E5410. running Vista Ultimate 64
BIOS flashed to latest version
Question by:martin2123
    LVL 22

    Expert Comment

    by:Dr. Klahn
    Is the second CPU visible to the BIOS setup screens?

    Occasionally there are BIOS problems causing system misconfiguration.  To check this, turn off the power supplies (or pull the AC cords if there are no switches) and remove the BIOS RTC battery.  If there is a "clear BIOS" jumper, set it; if not, wait 10 minutes.  Reinstall the battery, restore power, reboot, reconfigure the BIOS settings, start Windows and see if the second CPU is visible.

    If the BIOS still does not see the second CPU, it is possible that the second CPU has failed.  Have your hardware tech remove the second CPU and confirm that the system still starts normally.  Then swap the primary for the secondary CPU.  If the system fails to start, the secondary CPU has failed and must be replaced.  If the system starts, then the secondary CPU is OK, both CPUs can be reinstalled, and other avenues can be investigated.

    Author Comment

    Thanks for the prompt response.

    Pulled the battery and reset the bios.
    After bbot the bios reset it self but still only detected 1 cpu so no going to remove the second cpu
    will keep you posted


    Author Comment

    Second CPU removed and machine booted as per normal

    Swapped cpu's ove so the second is in the first slot and again machine boots ok, am i looking at a faulty motherboard?
    LVL 22

    Expert Comment

    by:Dr. Klahn
    It's certainly possible that the motherboard is faulty, given that both CPUs are known to be working.

    Were these CPUs previously working in the dual-CPU configuration, or was the second CPU just added or replaced?  If the second CPU was just added, it's probable that there is a CPU revision or stepping level mismatch.

    If the CPUs were previously working dual-CPU, do the BIOS setup screens have the facility to show whether two CPUs are installed?  If the system previously worked, but the BIOS now only shows one CPU, then there are just a few possibilities:

    1.  A BIOS setup option disabled the second CPU.
    2.  A motherboard hardware option (jumper, voltage regulator module) disabled the second CPU.
    3.  The motherboard has developed a fault.

    Author Comment

    This may be hard to belive but the machine is about 3 years old. It has been working and still does work, its possibly the first time i have checked the device manager and spotted the fault, so in theory could have been shipped like this?
    Supermicro has monitoring software. it detects cpu votages for both cpu's ???
    Cannot see anything in the Phoenix bios for enable/disable cpu's, cores, ht.
    No mention on the supermicro manual as to any jumper settings for enable/disable cpu..

    So it looks more like a fault with the MB
    LVL 22

    Accepted Solution

    There are two more possibilities:

    See the BIOS setup "Advanced" page, on the "Advanced Processor Options" menu.  Check the "Core Multi-Processing" option and confirm that it is enabled.

    It is extremely unlikely, but the BIOS may have been corrupted.  Normally the BIOS would detect that at startup; however, since the balance of probability now indicates a motherboard problem, and the motherboard is out of warranty, re-flashing the BIOS is the last thing to try.  The current BIOS is version 2.1a and can be obtained on the Supermicro web site.

    I suspect that you will end up ordering a replacement motherboard.  They are available on fleabay as expensive singles or moderately priced sets of three.


    Author Closing Comment

    Thank you for your help on this, sometimes just having a second opinion that is similar to your own (that you dont want to admit) is really helpful


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