PC requirements for Forza Horizon 4 Has been officially revealed in Windows Store
Minimum
OS Windows 10 version 15063.0 or higher.
Architecture x64
Keyboard Integrated Keyboard
Mouse Integrated Mouse
DirectX DirectX 12 API, Hardware Feature Level 11
Memory 8 GB
Video Memory 2 GB
Processor Intel i3-4170 @ 3.7Ghz OR Intel i5 750 @ 2.67Ghz
Graphics NVidia 650TI OR NVidia GT 740 OR AMD R7 250x
Recommended
OS Windows 10 version 15063.0 or higher
Architecture x64
Keyboard Integrated Keyboard
Mouse Integrated Mouse
DirectX DirectX 12 API, Hardware Feature Level 11
Memory 12 GB
Video Memory 4 GB
Processor Intel i7-3820 @ 3.6Ghz
Graphics NVidia GTX 970 OR NVidia GTX 1060 3GB OR AMD R9 290x OR AMD RX 470
Source
Minimum
OS Windows 10 version 15063.0 or higher.
Architecture x64
Keyboard Integrated Keyboard
Mouse Integrated Mouse
DirectX DirectX 12 API, Hardware Feature Level 11
Memory 8 GB
Video Memory 2 GB
Processor Intel i3-4170 @ 3.7Ghz OR Intel i5 750 @ 2.67Ghz
Graphics NVidia 650TI OR NVidia GT 740 OR AMD R7 250x
Recommended
OS Windows 10 version 15063.0 or higher
Architecture x64
Keyboard Integrated Keyboard
Mouse Integrated Mouse
DirectX DirectX 12 API, Hardware Feature Level 11
Memory 12 GB
Video Memory 4 GB
Processor Intel i7-3820 @ 3.6Ghz
Graphics NVidia GTX 970 OR NVidia GTX 1060 3GB OR AMD R9 290x OR AMD RX 470
Source