screen goes black when using hdmi

[froller2]

hey guys whenever i open a 1080p video while using hdmi my screen goes black for a second and returns to normal same when i close the video it happens in any media player and in every browser.
when i use vga it doesnt happen, tried mutible hdmi cables

 

[froller2]

forgot about specs:
intel core i5 3570k
gtz 760 2gb
16gb ram
ssd evo samsung
hdd seagate barracuda 2tb
mobo gigabyte z77x d3h
monitor AOC 2450w

 

[froller2]

anyone