Graphics Card is detecting the third monitor

I got a NVIDIA 1080 Titan X with 11 GB graphics card and I am using Ubuntu Linux. I wish to use three monitors but the graphics card can detect only two monitors.

I got two monitors connected by HDMI and one by DVI. All the monitors have the same make and model.

The graphics card got 3 displayports, 2 HDMI and 1 DVI.

I am wondering if anybody will be able to assist me.

Most likely the dvi port is identical with one hdmi port, i.e. they can be used either or, not both. This depends on the manufacturer of the card and should be noted in the manual.
For further info, please run nvidia-bug-report.sh as root and attach the resulting .gz file to your post. Hovering the mouse over an existing post of yours will reveal a paperclip icon.
https://devtalk.nvidia.com/default/topic/1043347/announcements/attaching-files-to-forum-topics-posts/

Thanks very much for your reply. I got this now. It is finally working.