I have used 6 x 4GB 2Rx8 PC3L 10600R (HMT351R7BFR8A) without any problems and tried to change to 6 x 32GB 4Rx4 PC3L 10600R (HMT84GR7MMR4A, original DELL), but this does not work. The server does not boot with it.

Can anyone explain this incompatibility?