Quote from: millerfilm on December 03, 2017, 06:11:40 AM

I see the settings for Frequency under the Antminer's Settings. It is set to the default, 384M. To make sure that I am understanding this correctly, going up in number, like 400M, 425M, etc. would overclock. So, going down, like 362M, 344M, etc. would underclock the miner.
Am I correct with this?

YES

Quote from: millerfilm on December 03, 2017, 06:11:40 AM

And, if underclocking, is that okay with the Antminer warranty? I know that overclocking voids the warranty.

MAYBE

Quote from: millerfilm on December 03, 2017, 06:11:40 AM

If underclocking is okay, are there optimal frequencies to use?

You have to find out the optimal frequency by yourself , where your miner going to be stable , the miner stability can be depend on ambient temp , humidity , frequency , power quality , power stability ..... There is no rule what is ok for my miners is going to be ok for yours !

Quote from: millerfilm on December 03, 2017, 06:11:40 AM

And, does anyone know if there is a chart, or guidance, that would give me an idea what the relation would be between L3+ Frequency and Hashrate?

Lower frequency - lower hashrate - lower power usage - less generated heat
There is no rule what is ok for my miners is going to be ok for yours !