Why Morning Intake Temperature Matters More Than Annual Average

When operators quote “average winter temperature” for a highland site, they often smooth over the hour that actually matters: the first intake pull after a clear, windless night.

During a November visit to a Hoengseong warehouse running 0.07 PH/s air-cooled units, our loggers recorded intake air at 3 °C at 06:40 — then −1 °C by 07:15 as ground-level cold pooled against the north wall louvers. Hashrate dipped 6% across the row before firmware recovery kicked in.

What we measured

• Intake probe placement 30 cm inside the louver face
• Exhaust temperature held steady, indicating the issue was inlet-side, not chip junction overload
• PSU fan speeds increased but did not compensate for denser cold air reducing heat transfer at hashboard heatsinks

Practical takeaway

Size intake ducts for the lowest hourly intake, not the monthly mean. If your weather station is 4 km away at a higher elevation, install a logger at the louver for two weeks before commissioning.

Commissioning checklist

1. Log intake hourly for 14 days pre-install
2. Note wind direction on mornings with >5 °C drop from sunset to sunrise
3. Compare firmware throttle logs against intake curve
4. Delay full-row startup until you have one complete cold-night dataset

This single morning window caused more downtime across our 2024 visits than any mid-day heat event.