There you go:
Grand Theft Auto V Minimum System Requirements
•OS: Windows Vista 64-bit
•CPU: Intel Core 2 Quad Q6600 2.4GHz or AMD Phenom 9850 2.5GHz
•RAM: 4GB System Memory
•GPU RAM: 1GB Video Memory
•GPU: Nvidia GeForce 9800 GT 1GB or AMD Radeon HD 4870
•HDD: 65GB Free Hard Drive Space
•DX: DirectX 10
Grand Theft Auto V Recommended System Requirements
•OS: Windows 8.1 64-bit
•CPU: Intel Core i5-3470 3.2GHz or AMD FX-8350 4.0GHz
•RAM: 8 GB System Memory
•GPU RAM: 2GB Video Memory
•GPU: Nvidia GeForce GTX 660 2GB or AMD Radeon HD 7870 2GB
GTX 660 + lower end quad core CPU will do for high settings.