UP2516D UP3216Q win10 two Monitors. UP3216Q power off out of connect

I got two Monitors setting up in win10 all DP interface. When UP3216Q power off it will out of connect (basically to save power). But if UP2516D power off it still connect all time. How can make UP3216Q Like UP2516D  Monitors?

Not the DB cable problem (I swop two cables to test)
Not the Nvidia DP socket problem (I swop two sockets to test)
Not the win10 main screen problem (I swop to UP3216Q become main screen, power off UP2516D, UP2516D still connect. Power off UP3216Q, UP3216Q lost connect.

Also If UP3216Q using HDMI cable connects. It always connects, like the UP2516D. So I think it maybe is the screen hardware or the driver program problem.