Here are the Far Cry 4 System Requirements (Minimum)
CPU: Intel Core i5-750 @ 2.6 GHz or AMD Phenom II X4 955 @ 3.2 GHz
CPU SPEED: Info
RAM: 4 GB
VIDEO CARD: NVIDIA GeForce GTX 460 or AMD Radeon HD5850 (1GB VRAM)
DEDICATED VIDEO RAM: 1 GB
PIXEL SHADER: 5.0
VERTEX SHADER: 5.0
OS: Windows 7 SP1, Windows 8/8.1 (64bit versions only)
FREE DISK SPACE: 30 GB
SOUND CARD: Yes

Far Cry 4 Recommended Requirements
CPU: Intel Core i5-2400S @ 2.5 GHz or AMD FX-8350 @ 4.0 GHz or better
CPU SPEED: Info
RAM: 8 GB
VIDEO CARD: NVIDIA GeForce GTX 680 or AMD Radeon R9 290X or better (2GB VRAM)
DEDICATED VIDEO RAM: 2 GB
PIXEL SHADER: 5.0
VERTEX SHADER: 5.0
OS: Windows 7 SP1, Windows 8/8.1 (64bit versions only)
FREE DISK SPACE: 30 GB
SOUND CARD: Yes