what if i have 3 GPU cards , do i have to connect them all to TV in order to review GPUs temperature ?

No, just need to connect 1 video card, Even if you have 1, 3, or 7 cards.

currently my HDMI is connect into my mobo , which is Intel i think .

can i connect my HDMI cable into my GPU and simultaneity mining

yes, try connecting the Monitor, from the video card, not from the Motherboard.

many thanks mate , i truly appreciate your help