Probably not. To increase clock speeds, you'll (generally) need to increase voltage (which is overclocking). Added voltage = more heat. It's unlikely the BIOS would allow you to overclock, so it's probably a moot point. Considering more voltage = more heat and the fact All in Ones can barely cool their stock components, it's just a bad idea all round.
Which all in one do you have specifically? The only Acer AIO I know of with a 1.6GHz CPU is an N3150 ..... which actually "boosts" to 2.08GHz (ie 2.1GHz), which should be sufficient for the requirements of this home job.