Is the RAM on Intel's list of compatible hardware or conversely found on the RAM manufacturer's list of suggested RAM?
Compatible hardware with Intel Workstation Board S5520SC is listed on a linked PDF following this link:
A company like Kingston would suggest the following, some of which can be found on Intel's tested list:
What RAM are you trying? I also have an S5520SC under my desk.
Crucial CT25664BA1339 2GB 240 P/N DIMM 256MX64 DDR3.
Others have said that perhaps I need to update the BIOS and I have tried to do this to no avail.
I checked the model of the memory you are using and it seems that these modules are Non-ECC modules, and that the modules are rated for Desktop systems.
Intel always recommends the use of validated hardware to avoid unforeseen issues.