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
I have 1 1660 super with hynix memory (MSI ventus xs) and i can get it run to 32 Mhs using -502 core and memory at 62% power limit. The driver i am using is the 446.14 version and it's stable for mining since june last year if i remember correctly. If you think it's driver issue then you can try to download another driver version but are you sure you have the hynix memory? not micron or samsung?