It depends on memory manufacturer. It looks like that you have Hynix memory. If it`s so - you ought to downclock memory to -502.
I underclocked it, with no effect, unfortunately
It is Hynix memory. So I guess I'm stuck at 20 MH/sec ? Or should I try a BIOS flash as proposed earlier ?
I have colorful 1660 super with hynix. -502 on memory gives me 31+ MH/S.