Asrock Taichi 6800XT low hashrate help!

When I set core=1240 mem=1065 for Asrock Taichi 6800XT, the hashrate drops. But when I set core=1200 vdd=800 mem=2150, I get 59.31 M

h/s. What should I do to get 64?

Hi,
Check this:
Core 1250
Mem 2150

Thank you. But I haven’t tried those settings. I set the latest core:1250 vdd:675 mem:1050. 62.20mh output