4GB (1x4GB) RAM Memory for Lenovo Essential C540 Series A25 | eBay
16GB KIT (2 x 8GB) for IBM-Lenovo Essential Desktop Series C540 All-in-One. SO-DIMM DDR3 Non-ECC PC3-12800 1600MHz RAM Memory. Genuine A-Tech Brand. at Amazon.com
Lenovo C540 23-inch All-in-One Desktop PC - (Black) (Intel Core i5 3330 2.7GHz Processor, 4GB RAM, 1TB HDD, No description (Bar… | Lenovo, All in one pc, All in one
Lenovo All-In-One C540 SSD Upgrade - How to : Basic | LapFix - YouTube