For hobbyists such as myself, the capital cost of already-owned (and obsolete) Xeons are infinitely less than replacing an otherwise-functional (albeit cooling-only) AC in a sub-tropical rainforest climate (like mine), which only has a few weeks of annual frost (snow "sticks" once every decade).

As far as placement of the machine: underneath your computer desk is ideal, as this directed heating allows you to keep the house's thermostat a few degrees cooler.

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If anybody were to ask me "what would you BUY to mine monero@home," I would definitely tell them to [instead] buy a heatpump-heater, -watertank, -&c (presuming they don't have each, already).