just don't go screaming ATI sucks if you kill your card with such a high memory OC. not many (non-benchwhore) people around here would push their memory that high - especially since it won't benefit you at all.
Don't worry- my 24/7 clock for memory was 1000mhz, but memory was able to do 1165 at previous one... So this haven't kill it

Did u find the limit of the core?
About 855-860mhz!