To make it work in theory, your 16gb RDIMM's would have to be in A2, B2 or A3, B3 since these are single channel lanes. A1,A4, B1, B4 are channel 0., A2, B2 are channel 1, A3,B3 are channel 2.   You may also receive an error during POST that this configuration is not optimal. You will have to manually go past this error and server may work properly since this configuration is not considered optimal.  The user's guide will show the optimal configurations: [URL]   page 117. Regards,
Hello,  I am wondering if the following memory configurations are possible for a Dell R510: BANK A BANK B A1 4GB B1 4GBA2 4GB B2 4GBA3 4GB B3 4GBA4 8GB B4 8GB BANK A BANK B A1 4GB B1 4GBA2 4GB B2 4GBA3 4GB B3 4GBA4 16GB B4 16GB The reason I am asking is that the manual states: 'Memory modules of different sizes can be mixed in A1-A4 or B1-B4 (for example, 2-GB and 4-GB) (..)" In this ([URL] thread, that doesn't seem to work. Currently the R510 had 2 processors and the 3x 4GB in slots A1,2,3/B1,2,3. We want to put 2x8GB or 2x16GB in slot A4/B4. 
R510, mixed RDIMM modules