My experience for your info:
When we try to increase the memory on our R710 from original 24 GB add another 48 GB, after adding the memory modules the server can not power up.
It's end up that the new module can not be added to the second bank of the emply slots. We need to remove the first (6 x 4 GB) and install the (6 x 8 GB) on ther first bank of slot and move the (6 x 4 GB) to the second bank of the slots. After that our ESX4i working again.