Hmmm.
Technically it should work but I'm not 100% convinced to be honest.
The VBIOS is 5 years old.
There is an slightly newer VBIOS available: 86.02.15.00.01 - dated 2016-07-11.
https://www.techpowerup.com/vgabios/186001/nvidia-titanxpascal-12288-160711So you could use the NVFLASH tool to update your Titan X.
https://www.techpowerup.com/download/nvidia-nvflash/But just be aware there is a risk you could break your Titan X if flashing fails. I have also read there is some issue with the small size of the VBIOS chip on the Titan X.
In that it cannot fit the full fat version of UEFI code onto it.
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Anyway the graphics card to one side... I would go back to troubleshooting basics.
- Remove EVERYTHING apart from the 24pin power cable.
So no GPU, CPU, Memory, M.2 drive and disconnect all SATA cables.
Just remember to plug the 4 or 8pin CPU power cable back in afterwards when you fit the CPU back.
- Then update the motherboard's BIOS via USB flashback to 7704.
- Then fit just the 3900X, CPU Cooler, one single memory stick to the A2 DIMM slot (second slot in), and the Titan X.
- Then power up and see if anything is being displayed. (try all the video outputs you can, DP, HDMI, DVI).
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If you are still getting no display at this point then I would be trying a newer graphics card.