When your system is booted, open RivaTuner once more and go again into the first option in Driver Settings. Then drag the slider up, 50MHz. Do not move the Memory clock. I recommend you don't uncheck "Link clocks". If you do, that is ok, but make sure the Shader clock is set to at least double the speed of the core clock or it will malfunction. DO NOT overclock the memory, you will get numerous errors. Anyway, setting the shader clock higher will yield better results than the core clock.
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