ASUS GTX560 TI TOP and BenQ G2420HDBL problem

I have problem with my setup. I have ASUS GTX560 TI TOP as GPU and BenQ G2420HDBL as primary monitor. My monitor is blinking, not whole, but like the bottom of it. I have also TV connected to my PC with HDMI and theres no problem. It seems to me that the backround led is blinking or something, but im not sure.

I have video of my problem:

http://www.youtube.com/watch?v=IAtg2Fhx28Y

You can see problem at times 0:15-0:18, 0:40-0:42 and 0:50-0:54.

I have had this problem for a while now and i have tried to solve it with different methods:

- I have changed my monitor to another one from BenQ warranty. Same happens with this one.
- I have tried using monitor with other cables (HDMI, two different DVI's, VGA). No help.
- I have changed the cable place from my graphics card. No help.

I was wondering, wud the problem be with this specific set of display and GPU, not with just one? Or can it be just that the other monitor is just blinking and theres no problems with the other monitor, but it's still GPU problem?

I wouldnt like to send my GPU to warranty, because i dont have another one and i need computer daily.

If anyone understood what i just wrote, and knows how to help, i would be thankful.