Since X99 mobo's all have 8 DIMM slots, the claims of 128 GB RAM are based on the assumption that there are 16 GB sticks available. That still is a dream and if these appear on the market, they will be astronomical in price, while at the same time force the price of 8 GB sticks down.
Asus X99 DeLuxe and WS are popular boards. Good SSD's are the Samsung 850 Pro and the Crucial M600. Good HDD's are the HGST Ultrastar and Seagate Constellation ES enterprise drives. A dedicated raid controller is faster than on board, gives less burden on the CPU, has bigger cache and offers parity raids. Raid5 on-board is no good.
thanks for your reply
what about an x79 system if i can't afford more than 16GB of ddr4 for x99 ? isn't more RAM almost always more important than other considerations ?