Sun T5120: Memory issue with 8GB DIMMs, "Unsupported memory configuration"

I'm trying to upgrade RAM in a Sun T5120 server, replacing 2GB (Sun P/N: 501-7953-01) with 8GB DIMMs (Sun P/N: 511-1262-01).

When bringing up the host system, I get the following errors on the ILOM:

-> show faulty
Target              | Property               | Value                           
--------------------+------------------------+---------------------------------
/SP/faultmgmt/0     | fru                    | /SYS/MB                         
/SP/faultmgmt/0/    | timestamp              | Dec 14 15:29:42                 
 faults/0           |                        |                                 
/SP/faultmgmt/0/    | sp_detected_fault      | /SYS/MB/CMP0/MCU3 Forced fail   
 faults/0           |                        | (IBIST)                         
/SP/faultmgmt/0/    | timestamp              | Dec 14 15:29:28                 
 faults/1           |                        |                                 
/SP/faultmgmt/0/    | sp_detected_fault      | /SYS/MB/CMP0/MCU2 Forced fail   
 faults/1           |                        | (IBIST)                         
/SP/faultmgmt/0/    | timestamp              | Dec 14 15:29:13                 
 faults/2           |                        |                                 
/SP/faultmgmt/0/    | sp_detected_fault      | /SYS/MB/CMP0/MCU1 Forced fail   
 faults/2           |                        | (IBIST)                         
/SP/faultmgmt/0/    | timestamp              | Dec 14 15:28:59                 
 faults/3           |                        |                                 
/SP/faultmgmt/0/    | sp_detected_fault      | /SYS/MB/CMP0/MCU0 Forced fail   
 faults/3           |                        | (IBIST)                         
/SP/faultmgmt/1     | fru                    | /SYS                            
/SP/faultmgmt/1/    | timestamp              | Dec 14 15:29:42                 
 faults/0           |                        |                                 
/SP/faultmgmt/1/    | sp_detected_fault      | Dec 14 15:29:42 ERROR:          
 faults/0           |                        | Unsupported memory              
                    |                        | configuration

As you can see, the only error message I get is "Unsupported memory configuration".

Note that I'm absolutely sure that I placed in the DIMMs in the correct slots.

Might this issue be related to the Voltage of the DIMMs? Any suggestions on how to trouble-shoot this issue?

This issue seems to be similar to the one explained at "Inserted disabled" while upgrading Sun Sparc t5120 memory. However the given link http://docs.sun.com/source/820-4445-10/chapter1.html seems to point to an inexistent page...

This is what the SUN manual has to say on T5120 memory

FB-DIMM Configuration Guidelines

Use the guidelines described in this topic when installing, upgrading, or 
replacing FB-DIMMs:

* There are a total of 16 slots that support industry-standard FB-DIMMs.
* Supported FB-DIMM capacities are 1 GByte, 2 GByte, 4 GByte, and 8 GByte.
* Valid quantities of FB-DIMMs are 4, 8, or 16.
* All FB-DIMMs in the server must be the same capacity.
* All FB-DIMMs in a branch must have the same part number.
Note - FB-DIMMs that run on 1.5V are not supported in this server. An FB-DIMM 
that runs on 1.5V is sometimes noted with an LV on the part number label. Do not
install such FB-DIMMs in this server.