Best Deal from Amazon.com : https://www.amazon.com/gp/product/B00PRW1258?tag=chriskressera-20
4GB Dual Rank NonECC RAM Memory Upgrade for Sony VAIO VPCEC3DFXBJ by Arch Memory
Product Description :
Arch Memory is a Registered Trademark of Arch Computer LLC
Bus Type PC-8500
Data Transfer Rate 1066Mhz
Pins 204 Pin
Any configuration up to 8GB can be reached using any combination of 2GB and 4GB modules