Dell Alienware X51 R3 AX51R3-6510BLK Desktop PC with Intel Core i5-6400 Processor, 8GB Memory, 1TB Hard Drive and Windows 10 Home (Monitor Not Included) - Walmart.com
CMS 32GB (4X8GB) DDR4 17000 2133MHz Non ECC DIMM Memory Ram Upgrade Compatible with Alienware® X51 R3 - C62 at Amazon.com
Alienware X51 R3 System Specifications | Dell Singapore
8GB Memory for Alienware x51 R3 Desktop DDR4 PC4-17000 2133 MHz Non-ECC DIMM (PARTS-QUICK Brand) at Amazon.com