Suddenly my PC won't detect second monitor

[tavis15]

Suddenly my second monitor is no longer detected. This happened about a week ago but seemed to have fixed its self after a couple restarts. I have swapped monitors and everything is fine with screen. I have installed old graphics card drivers. The cord goes from a mini display port to a DVI-D. The card is a GTX 970 and I'm running windows 10 64 bit.

It's been working great for months and then all of a sudden it stopped.

Any

 

[tavis15]

I unplugged both my main ans secondary monitors and plugged them back in and they worked again until I rebooted my pc. Once again my PC wont even detect the monitor. At least I know its not the cord or connection. Has to be something with the software.

Any Ideas?