CPU mismatch LED appears after adding second processor - IBM eServer xSeries 235

Resolving The Problem

RETAIN tip: H176802

After adding the second processor:

• The CPU Mismatch LED appears and the machine will not complete POST.
• There is no video.
• The server will post with processors installed one at a time.

The system has the symptom(s) described above, and may be any of the following IBM eServer xSeries:

• an IBM eServer xSeries 235, type 8671, any model
• The system has two (2) microprocessors installed
• The microprocessors are at different stepping levels
• The CPU with the higher stepping level is in Socket 1 (U13)
• The ISMP firmware version 1.03 is affected
  
  

1. Remove the microprocessor in location U9 (and set aside until step 3).
2. Move the microprocessor in location U13 to location U9.
3. Place the microprocessor removed in step 1 (from location U9) into location U13.
   
   

Version 1.03 of ISMP firmware checks the stepping level of the processors. If the lowest stepping level processor is not in the boot strap processor socket (CPU 1 Socket, U13) then the machine will not POST and the CPU Mismatch LED will appear. The ISMP firmware version 1.04 and later removes this check. In the future, the system BIOS will provide this check and a message will appear during POST to switch the processors.