After speaking with an Intel rep this NIC does not have a built in DMA engine.
Does it provide some other data transfer mechanism that allows for programming the controller to specify source address, destination address, and buffer size (i.e., # bytes)
to selectively xfer large chunks of data using the x520 resources without impacting CPU performance?
Thank you for contacting Intel.
You may explore the different advance options available for our 10 Gigabit Adapters for large send offloads.
http://www.intel.com/support/network/adapter/pro100/sb/CS-029402.htm Intel® Server Adapters — Advanced Driver Settings for Intel® Ethernet 10 Gigabit Server Adapters
Hope this helps.