Go to crucial.com, select Dell, then PowerEdge, then R710. This will show you the specs (Intel standard specs for a Xeon 5500 or 5600 series proc), as well as guaranteed compatible memory.

Note: it supports registered and unbuffered dimms, but you cannot mix them in a single system. To find out what you currently have, you'll need to check the bios, use OpenManage Server Administrator or check your order details (assuming nobody changed the memory since purchase). With these methods you can also find how many dimmslots you have open and what ranking you have for options to add memory.

Our system came configured with 12 GB using 2 GB UDIMMs.  They were 'hynix' branded with the following "2 GB 2Rx8 PC3-8500E-7-10-E0" "HMT125U78FR&G - G7 T5 AA-C 1008".  We had an issue with some of these and replacements were "ELPIDA" "2GB 2Rx8 PC3-8500E-7-10-E1" "EBJ21EE88DFA-AE-F 1014GL766492".

There are other things to consider when installing the RAM.  With the R710 it uses triple channel RAM but if you fill all of the slots then the speed drops ( even partially filling the slots will drop the speed ).  Also there are several RAM Modes available in the BIOS: Optimizer Mode; Balanced Performance Mode; High capacity Mode; etc.  Depending on the BIOS Setting this will effect the RAM installed.

Do a Google for DELL 11th Gen Memory and read the white papers.  Even with the help of a DELL Tech. we had difficulty getting what we wanted/expected...