Please see the datasheet of Intel Broadwell-DE.
http://www.intel.com/content/www/us/en/processors/xeon/xeon-d-1500-datasheet-vol-3.html (Eg datasheet-3 page 26: description of SUSACK_N) "Intel® Xeon® Processor D-1500 Product Family-based platform doesn’t support Deep Sleep Power state"
What is this deep sleep mode?
Your particular Intel(R) Xeon processor does not have C3 Sleep mode, which is useful on laptops or when you computer/server is not going to run for long periods of time. Idle States (C-states) are used to save power when the processor is idle. C0 is the operational state, meaning that the CPU is doing useful work. C1 is the first idle state, C2 the second, and so on, where more power saving actions are taken for numerically higher C-states.