>Is there a way to find out if ram memory was previously overclocked ?
>
No.
>I have some utility tests as memotest and other but how to see if memory
>was overclocked before my usage ?
It doesn't matter if it were overclocked, either it works
now or it does not. One remaining factor would be if it
were overvolted (or used in an improperly cooled system)
such that the heat caused structural problems with the
chip-PCB bond on surface mount chips, or degradation of the
chip package itself - but it could happen running at the
proper clock speed as well and unless there is a visual hint
of excessive heat, no way to determine this either except
perhaps someone trained to find the problem and being able
to compare with same modules known to not be subjected to
that stress.
>
>Moreover, what kind of effects could that do to using that memory again
>at normal timings and frequency?
None. For practical purposes either it works or doesn't.
If the above heat degradation occurred, it could reduce the
lifespan of the memory but this is not very common. In
general it should be no concern whether it was overclocked
or not so long as it now runs at the spec'd speed - though
your motherboard is the second variable in that, whether it
can run JEDEC spec'd memory stabily as some boards are more
picky about multiple modules and/or timings used, and
sometimes bios updates are issued to address these problems.
memory-was it overclocked ? 
Linear Mode
