Safe HD 6950 Overclock Advice

[Jamin2]

I have a VTX HD 6950 whose shaders cannot be unlocked to those of a 6970 (believe me I've tried). I cannot find advice anywhere online of what a safe overclock is for an HD 6950 that hasn't had its shaders unlocked. I only want to use Catalyst Control Center as I don't like fiddling with voltages. Please help!

Thank you.

 

[Consciencekills]

I have a HIS Ice Q 6950 which i was able to Overclock to 885mhz core clock and 1325mhz core clock.
no problems has been overclocked for about 6 months now.
temps idle at about 38-40 C and max at around 65-70