I have a nvidia gtx 780,and its written DX11 and with 900 series they are rolling out DX12, is DX a software or hardware, will it upgrade through software update?
Yes, every DX11 card will be able to run DX12, you just need to have the correct OS (win10, 8/8.1.. I can't confirm about win7 as every week there's a rumour about going or not to be supported).