I bought 256MB PowerColor ATI Radeon 9600 PRO EZ. At first I didn't have any problems. I played Heroes V for hours at 1024*768 resolution and image quality setting at normal. But after a few days later I began to have a monitor flicker problem. My monitor is Samsung 793DF. At startup it doesn't flicker but after I play for some time it does. I downloaded the latest catalyst but it didn't solve the problem. Could it be a heating problem. If it is then why the monitor didn't flicker at first days. Also the problem started after my friend played with the general opengl and direct3d settings, but after that I re-installed the drivers and even formatted windows but the problem still exists.
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It's probably your refresh rate, try changing it.
I tried even 60hz it is not refresh rate. Anyway I tried another monitor and then tried 9600pro at another system and the problem existed at both cases. so the problem was at graphics card and I changed it. (the store I bought it also tested it) I wonder what the problem was.