Just installed the new rivatuner in vista64, I went to the overclocking tab and I try 750 mhz core (default 730), when I click ok it reverts to default, so I try 745, 740, 731, still reverts to 730. So I downclock to 700mhz and yup you guessed it right, back to default. I try overclocking the memory, same results I untick link clocks and up 50mhz on the shader clock, IT WORKS, it goes up to 1650 from 1450 default. Thing is now I can overclock the core and memory 800/1230, but if I don't overclock the shader, I can't overclock core or memory.
Installed latest drivers, same problem I've found that there's some kind of threshold between the core and shader clock. I need to overclock the shader at least 50 mhz for core overclocking to work, else it wont overclock even 1mhz To reach 780 core i need the shader to go at least 1560mhz. Since I haven't had a 8000 series card I don't know if this is normal, I assume it is. Still it puzzles me that I have to overclock the shader clock to be able to overclock the core and memory at all.