This part is a kind of semiconductor called K4B4G1646D.

Function of this product has 4Gb D-die DDR3 SDRAM.

Manufacturers : Samsung

Image and pinout :

Some of the text within the PDF file :

Rev. 1.02, Feb. 2014 K4B4G1646D 96FBGA with Lead-Free & Halogen-Free (RoHS compliant) 4Gb D-die DDR3 SDRAM Only x16 datasheet SAMSUNG ELECTRONICS RESERVES THE RIGHT TO CHANGE PRODUCTS, INFORMATION AND SPECIFICATIONS WITHOUT NOTICE. Products and specifications discussed herein are for reference purposes only. All information discussed herein is provided on an "AS IS" basis, without warranties of any kind. This document and all information discussed herein remain the sole and exclusive property of Samsung Electronics. No license of any patent, copyright, mask work, trademark or any other intellectual property right is granted by one party to the other party under this document, by implication, estoppel or otherwise. Samsung products are not intended for use in life support, critical car [ ... ]

K4B4G1646D PDF Datasheet Download