Horizontal waves on my monitor display

[FONT=verdana]Hi. I have horizontal lines that scan my monitor whenever I play a game. I can see the horizontal lines only on darker colors like grey, dark-green etc. I have a Samsung E2220 display that runs at 1080p on 60hz on a vga cable (no hdmi/dvi support on it). I tried another few vga cables, I tried some other power cable but with the same result, the waves were there.[/FONT]
[FONT=verdana]I have all drivers updated (monitor and other hardware). My current PC specs are: AsRock N68-C S UCC, Phenom II x4, 4Gb DDR3, Radeon HD7770, 500gb HDD Sata3 and a power supply Sirtec 500W 80+.[/FONT]
[FONT=verdana]If I open Far Cry 3, for example, I get those horizontal lines. If I minimize the game I still get the horizontal lines if I have something dark on my display (a grey/dark-green/dark-blue website).[/FONT]

[FONT=verdana]Before the HD7770 I had a GTS 450 and had the same problems. Could it be the PSU, or the motherboard or what? I also tried a different display monitor (on the VGA) and had the same horizontal lines scaning my display monitor but on the DVI the problem [/FONT][FONT=verdana]disappeared. The thing is that my monitor doesen't have a DVI, only VGA.[/FONT]
[FONT=verdana]The monitor is a year old, still under guarantee same goes for the PSU and the other components. [/FONT]

[FONT=verdana]Sorry for my bad English, I hope that you can help me.[/FONT]
 
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