CMS 8GB (1X8GB) DDR3 12800 1600MHz NON ECC SODIMM Memory Ram Upgrade Compatible with Dell® Latitude E6540 Laptop/Notebook - A8 - Walmart.com
Amazon.com: Dell Latitude E6540 15.6in Laptop, Core i5-4300M 2.6GHz, 16GB Ram, 500GB SSD, DVDRW, Windows 10 Pro 64bit (Renewed) : Electronics
Amazon.com: Dell Latitude E6540 15.6-inch Business Laptop, Intel Core i7-4800MQ up to 3.7GHz, 8GB RAM, 500GB HDD, Radeon HD 8790M, HDMI, DVD-RW, Windows 10 Professional (Renewed) : Electronics
Dell Latitude E6540 disassembly and RAM, HDD upgrade options | MyFixGuide.com