This is a known bug that ATi's FAQ claims no fix for. The way to OC your card without the flicker is to use RivaTuner. The lates versions support Ati cards. That's how I OC'd my x1950. You can try ATi Tools which is separate from CCC but there have been some fan control issues with it (It slows down or turns the fan off)
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"There are only two types of ships- submarines...... and targets" Unknown
"you wouldn't catch me on a ship that deliberately sinks itself"- comment to me from a surface sailor. 
System:
AMD 6300 3.5 GHz | 32GB DDR3 | SATA 300 320GB HD, SATA III 1TB HD, SATA III 1.TB HD | ASUS Sonar DS sound card
NVIDIA 1660 Super OC | Windows 10
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