Make sure that the RAM DIMM slots are populated in the correct order (specified in letter sequence A through I) in the following link
https://support.hpe.com/hpesc/public/docDisplay?docLocale=en_US&docId=c01727710#N1051A
Although it is hard to see that the server would still boot up if the memory modules are populated in an incorrect fashion.
From the example of the 54GB it looks like it populates lower capacity RAM first before the larger ones (2GB in A to C, 8GB in D to I)