Overclocking has nothing to do with that. If you want more "heating", simply add more miners. By overclocking, you are simply over-stressing the units, basically burning them out, so don't be surprised if they fail in the middle of winter...

The rule for the voltages applies identically no matter the speed you are setting. ALWAYS find the lowest voltage where the hashboard is still hashing. Each hashboard is different. Normally the voltages required for overclocking are higher than normal or underclocking, but that doesn't necessarily mean above "factory" settings. Again every hashboard is different, and a more efficient hashboard can usually take more of a beating as well.

There is no single universal setting, beyond starting points. You have to always find out the correct setting for each board; yes, manually. It is my opinion than anything beyond 9v is not good, and that prompts for lowering the speed. But its your gear, you are the one burning it...

Also if the input air is too cold while the inside is too hot, you are going to get a thermal shock. Worse, condensation and 100c means vapor, by overclocking you are getting into that dangerous zone (water + electronics = short), that is probably the very reason they won't be changing the 95°C thing.

Rule of thumb is simple: Overclock = premature death; Underclock = prolonged life; both vs "normal" settings.