Hi, I'm upgrading from a 1070 FTW Hybrid to a 1080 ti FTW3 Hybrid but I'm currently not getting any signal from either the GPU or the iGPU. I think I rather naively thought I'd just be able to swap the cards out but it seems that there may be more to it. The main problem is that I'm not able to get a video output to unstall Nvidia drivers to get a clean install for the new card. I've reset the bios a few times (although only via jumpers and reset button - not by removing the LiOn battery). Was planning on reinstalling the old 1070 and see if I can get a signal from that to enable the driver removal etc. Also try HDMI (using DVI currently). My system hasn't changed at all except for the new GPU.
 
The PC powers up and the GPU appears to power up also.
My system details:
Mobo: Taichi Z390 ultimate
CPU: i7 9700k
RAM: 32gb Corsair Dominator DDR4 3000
 
Please let me know if you need any additional info.
 
Very grateful for any advice.
 
Thanks.

bob16314
The motherboard will auto-switch to using a graphics card when one is detected, so the processor iGPU graphics will be disabled until the card is removed or you manually set the primary graphics to be the iGPU in the BIOS.

There should be no problem swapping out the 1070 FTW Hybrid for a 1080 Ti FTW3 Hybrid..I suggest putting the 1070 back in and see if it works then..The 1080 may be faulty.

If you suspect the 1080 is faulty, try it in another compatible PC or take it to a PC repair shop for testing.
 
I would also make sure the motherboard BIOS is updated to the latest one.

You might also make sure the card isn't sagging in the PCIe slot and losing contact, lift up on it a little and see if it works.

+1