Originally Posted by M4rce
yes, I'm soon to change it ... I read on another side, it may be the cable to the monitor that is saturated with so much data and that the monitor has a lower refresh rate can cause this ... explains that it can be solved activating v-sync
I wanted to rule out that it was the gpu
I think the fact that you had this problem with the 7970 rules the GPU out.
Anyway, perhaps this problem is unique to this monitor, but I have never seen this and I have used a VGA cable to a VGA to DVI adapter before. I did that with a 22" Samsung 2253BW. It's a 9-year old LCD monitor. When I used the adapter, I was able to get the same perfect signal that I had with a DVI cable. The reason I had to use a VGA cable was, I had to order a new DVI cable because the one I had died on me, so I needed to use my VGA cable while I waited for the new DVI cable to arrive. This was just about 2 years ago, so yeah, cables can go bad.
Regardless, your monitor is 9 years old, so I strongly urge you to replace it as soon as you are able to. You don't want to wake up to a dead monitor and then be forced to buy a cheap one.