If I'm getting fret-rattle from the 12th to the 18th fret...?

[Superuser]

Does it mean that I have too much bow in the neck? I own a new lite ash strat (9.5" radius) and am setting it up. My relief is set a tad more than .25mm. No real buzz anywhere on any string, but I'm still getting some rattle from the 12th to the 18th fret on the D and G strings and is very prominent when overdriven. I've raised the saddles up pretty high.

any help would be appreciated.

Thanks

Lution