Solve the problem of sudden monitor standby in the game

Hello to all guys
I'm grateful tips do have a serious problem.
When I run Game Watch Dogs2 after a short time (20 to 45 minutes) monitor automatically goes to sleep while the graphics and CPU time. By pressing the mouse or keyboard still work no matter how hard I try to monitor the come out but does not affect sleep Here is the only way off the case and turn it back on. The other monitor I tested did not differ but the problem remains. Except for the game The Witcher 3 has already had this problem but do not know how it was resolved. I change the monitor cables still did not matter.
This is my system specs:
LCD: DELL P2210
Graphic Card: GTX970Astrix oc
Motherboard: asus gaming z170
Ram: 8GB DDR4
CPU:Ci7 6700K
OS:Win10Pro x64