Question Pc lagging whenever watching youtube or netflix movies

[passive]

So whenever i try and watch a movie on Youtube my pc slows down for no Reason and my monitor keeps Flashing off and on the same thing happens When on Netflix doing something Simple like browsing im very confused as to why and dont know how to fix it


Pc specs

gpu:EVGA 750 ti sc

cpu: i5 7400

ram: DDR4 8gb

 

[Shektron]

Update drivers for the GPU, update the BIOS as well, and maybe try changing the cable you are using to connect the monitor.