with >60% humidity points here on my country, high density only happens with water blocks).
I don't understand that statement, heat sinks don't care about humidity to cool, they care about temperature differential. They do NOT use evaporative cooling like humans do.
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Humid air increases static pressure on fans, lowering considerably the air pushed through the heatsink (that means CFMs go down by a whole lot).
Waterblocks OTOH don't rely on changing ambient conditions (if you're going closed loop).
There's also the possibility of open loop cooling with chillers and such, but i'm not a fan of that kind of cooling tech.