Horizontal waves on my 19" LCD Monitor.

[Noob PC gamer]

Hello, I bought a 19" ViewSonic monitor 2nd hand and a year old from the previous owner. Before I bought it, it works perfectly, no waves, no flickering and such. When I went home, I bought a VGA cable as it only has a VGA connector and same goes to my PC (No GPU so my only choice is VGA to VGA). I tested it on different machines and same problem occurs. I assume buying a GPU fixes my problem?

 

[WyomingKnott]

I don't quite understand. If you tested it on different machines and the same problem occurs, then it is most likely that the problem is in the monitor.

 

[Noob PC gamer]

I don't quite understand. If you tested it on different machines and the same problem occurs, then it is most likely that the problem is in the monitor.

But from when I bought the monitor, it works perfectly fine. I also have a thought that my 2 old power cords from an old PC used on both my PC and Monitor are the ones causing the problem, is that possible?
Also from what I remember the old PC's monitor was a CRT one from where the power cords came from.

 

[WyomingKnott]

When I bought my last car, it worked perfectly fine. Later, after being t-boned by a lobster truck (really, surf and turf), it didn't. Things happen.
The highest-probability cause when a monitor shows the same problem on different machines is the monitor. The next-highest is the video cable. The only problem I have ever seen caused by a power cord is when it isn't plugged in.
So I gave you my most-likely scenario.