SK Hynix 4GB DDR4 2666MHz SODIMM Memory Module at Amazon.com
Hynix PC3-12800 DDR3-1600 4GB Computer RAM for sale | eBay
Amazon.com: SK Hynix 4GB 2RX8 PC3-12800E 1600MHZ HMT351U7CFR8C-PB 00D4957 00D4955 47J0180 Compatible with IBM System x3100 M4 IBM System x3250 M4 : Electronics