[Question] [NVDIA] Here please read please!!!

I fan of AMD and this is my GFX Ati Radeon HD 4650 i switch to NVDIA because i see the performance and quality its awesome so this is my question

Hello Sir/Mam My Dad bought me NVDIA GeForce Gt730 i research in the internet where DX12 will invade the GAME but the problem is i know the NVDIA GeForce Gt730 is supported with DX12 but is there out or downloadable driver for DX12 and also will that affect if i go back to WINDOWS 8.1 my PC NOW is WINDOWS 10.

Is Directx12 is only FOR windows 10???