Some boards will disable the iGPU ports when there's a gfx card populating the PCIe x16 slot. Check if that is the case with your board.
The DVI-D and DVI-I should both produce the same digital signal. The only difference being the DVI-I (I=integrated) also contains pins for the analog signal needed for older VGA monitors.
Thanks clutchc, in that case I'll just use the dvi on my gpu.
UPDATE: yep, 144hz works perfect. The reason for all this was because I thought I had a bad dvi port on my gpu. When I first built my rig I was using a VGA to DVI adapter on an older monitor and was getting some bad atifacts, scanlines ect, but hdmi worked fine. I guess it was just the old adapter and vga cord not jiving with the 970s dvi port. Thanks again.