Do you need to replace your video card if there are diagonal lines going across your screen?

Hi Nicole,

It's not necessary. First check the physical connections and then try uninstalling the drivers and reinstall them. That helps mostly. Also perform a Monitor Self Test. This should help in isolating whether the problem is with the monitor or the display card. Feel free to get back to me at the above mail ID just in case, you wish to consult me in this regard.

A bad neon light ballast will cause those lines if it is close to the PC.

Another PC running close to your PC will sometimes do it too.