i downloaded ati tool 0.25 and coolbits 2.0 and tried to overclock my xfx 7900 gt. in ati tool as soon as i checked for fragmentation, it instantly with in the first second of testing started having errors and little yellow dots. i never see this in actual game play though. ati tool wouldn't overclock it even one mhz so i tried coolbits and when i either tried to slide the bar or do a test to find the highest clock speed. It wouldn't go anyfurther then what hte card was sent to me stock, 520/750. does anyone know how to overclock these xfx 7900 gt cards?