of no effect
Without any of the desired result or impact. Our warnings were of no effect, and he went ahead with the foolish investment.
to no effect
Achieving none of the desired result or impact. We warned them not to invest their money in such a foolish scheme, but to no effect.
of/to no efˈfect
not having the result hoped for: Their warnings were of no effect.They tried to persuade him to change his mind, but to no effect.