Originally posted by: rb7

This box is used for virtualization (IVM). We replaced 4 (2GB each) DIMMS with 4 (4GB each)new DIMMS. The system has 8 memory slots. Four of them have 2GB DIMMS and the other four have 4GB DIMMS. The problem is that the system does not boot. It shows B123F643 on operator panel. A quick google search shows

B123F643 The DIMMS in the callout list don't match, so they form an invalid memory group
(http://publib.boulder.ibm.com/infocenter/systems/scope/hw/index.jsp?topic=/ipha6/b1xxa.htm)

Don't know what it means. Do I need to reconfigure the memory. Are there any docs that explains how to add memory or configure them etc?
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Originally posted by: rb7

Problem solved.

I did not balance out the memory on the two quads (4 slots per quad) so the system would not come back up. So I did the following:

Quad 1
Slot1 2GB
Slot2 4GB
Slot3 2GB
Slot4 4GB
Quad 2
Slot5 2GB
Slot6 4GB
Slot7 2GB
Slot8 4GB
And the system came backup fine.

Following is some info that I found on one of the service manuals:

For optimum performance, the memory must be installed in the system in a balanced configuration, in that each processor card that is installed in the system, regardless of type, must have the same amount of memory installed. In addition, the following basic rules apply:

1 DIMMs must be installed in groups of four DIMMs (quads).

2 A quad of DIMMs must be all of the same size.

3 Quads are populated in DIMM slots 1, 3, 6, and 8 first and then slots 2, 4, 5, and 7.
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Originally posted by: SystemAdmin

Hey thanks for the info. This is similar to installing memory in banks on intel desktops.

r/
R
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