Monitor showing lines and black screen pop ups

[ShadowsVoid]

Turned my PC on, about an hour in from usage watching videos and the like, my screen just went black for a couple of seconds then went back.

Couple of minutes later it does it constantly with white/black horizontal lines appearing in. Should I be worried?

I have an MSI GTX 970 so it isn't exactly old, I have overclocked it with:
Power Limit: 110 %
Core Clock: +145
Memory Clock: +450
I've had it overclocked since I got it and no artifacts have been popping up.

The problem doesn't seem to happening now, only when watching videos.

I also have a 550W OCZ PSU and an i7 4770

thanks!

 

[DeputyJake]

Sounds to me like your video card is getting too hot. (Especially since it happens when you're watching videos.) Make sure the fan on it is still properly working. What are your temps?

Also, does it happen when you're gaming?