I believe you can (happy to be corrected) only do this with the Xeon CPU's not the HEDT ones in the current generation. That's why I was curious if anything in Broadwell-E was going to change that.
Subject to motherboard support (physical slots and bios) an x99 board with any haswell-e (or broadwell-e) chip can run 128GB of memory
http://www.pcworld.com/article/2938...s-pc-with-128gb-of-cutting-edge-ddr4-ram.html
128GB with a 5820k and an Asus mobo