This answer redirects to OpenXtra that suggests server rooms shouldn't run too cold. Google also suggests not going lower than 55°F, but doesn't go into details regarding why.
Given that:
- CPUs do work completely fine while in sub-zero temperatures.
- Hard drives will fail if going into uncommonly low temperatures (which won't be reached if living anywhere between northern Norway and southern Argentina).
- In general, electronics won't be ruined by cold, but by condensation and humidity.
Why would it be bad to run my server into an unheated basement as long as the temperatures aren't extremely low (-10°C to +15°C) and the air is reasonably dry?