IBM 8681 Hardware Maintenance Manual - Page 222

Note In the case of multiple FRUs, such as power supplies, processors, processor terminators, processor daughter boards, memory cards, and DIMMS, it is prudent to verify the function of each FRU in the same position or slot prior to installing multiples of the FRU. This way, you are working with known-good FRUs. A failure when multiples are installed indicates failure of the card the multiple FRUs plug into, or another related FRU, rather than the FRU you just installed. Consider these possibilities: 1. If all processors work in position A-1 but the system fails with processors in A-1 plus any other slot on processor daughterboard A, suspect the processor daughter board followed by the processor controller board. 2. If all power supplies work in position 1 but fail in slots 2 or 3, suspect the midplane or power control card. 3. If all memory DIMMs work in memory board A slot J1 but fail in any other slot, suspect the memory board, followed by the processor control board and the midplane. 4. If a populated memory card works in position A but fails in position B, suspect the processor controller board followed by the the midplane. Components should be added in the following order: 1) Front panel (after which you no longer need to use Jumper J11 on the I/O board to force power on) 2) Power supplies (one at a time) 3) Processors (one at a time) 214 Netfinity Server HMM