I have the same issue 20hash. I tried the memory and clock at anyway and still doesn't work better than 23.
I have the latest Nvidia drivers,
Can you confirm is due to the 452.06 version?
Regards
that's right the problem is in the driver version you are using, in version 452.06 it will work perfectly adjusting the memory to -502 and powerlimit to 62% reaching ~ 31mhs hashrate.