I've got a R4870 and Afterburner 2.10. When I set Core Clock to a value below 500 mhz, it resets to the previous value (780 mhz) without error message. Shouldn't there be an error message?
If you set it lower than what the CCC limits are, it will just jump back to whatever was set before without any error. Try reducing it in stages to find out what the lowest limit is. For example on my 5770 i can't go lower than 600, i try 599 and it just jump back (although it does go down to 400 with powerplay).
same prop here. but i think you cant set the speed that is set when msiafterburner is started i.e. defaultclock is 550 but when msiafterburner is started the clock is allready set to 600 and you set the clock to 650. then when you set 600 again it jumps back to defaultclock (550)