IERR is a Processor Internal Error; it is a signal that indicates a processor unrecoverable error or even a non-CPU event, such as a system BUS interruption or a memory can start this signal.
On the Intel® Server Boards listed at the bottom of this page, a Processor IERR can be confirmed or discarded from the BIOS (Basic Input Output System) Setup Utility under Advanced > Processor Configuration > CPU Retest.
The IERR Filtering Algorithm helps to determine if the IERR signal came from a false CPU internal error or from another hardware source, preventing unnecessary processor replacements and at the same time helps to isolate IERR events. If the IERR returns after the CPU Retest, the IERR signal most likely came from the CPU itself. Check the System Event Log (SEL) to find out which processor is generating the IERR, if you have more than one processor installed.
In some cases a system restart can also eliminate an IERR but if the problem persists please try to boot up the system with one processor at the time, test another processor if possible and remove and reinstall the memory.
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