Here are the Far Cry 3 System Requirements (Minimum)
CPU: Intel Core2 Duo E6700/AMD Athlon64 X2 6000+
CPU SPEED: Info
RAM: 2 GB
VIDEO CARD: Nvidia 8800 GTX/AMD Radeon HD 2900 or equivalent 512MB DirectX 9c card
DEDICATED VIDEO RAM: 512 MB
PIXEL SHADER: 3.0
VERTEX SHADER: 3.0
SOUND CARD: Yes

Far Cry 3 Recommended Requirements
CPU: Intel Core i3-530/AMD Phenom II X2 565 or equivalent quad-core
CPU SPEED: Info
RAM: 4 GB
VIDEO CARD: Nvidia GTX 480/AMD Radeon HD 5770 or equivalent 1024MB DirectX 11 card
DEDICATED VIDEO RAM: 1 GB
PIXEL SHADER: 3.0
VERTEX SHADER: 3.0
SOUND CARD: Yes