Thermal Paste Degradation in Units Above 0.05 PH/s
After 18 months of continuous operation, factory thermal paste on several popular ASIC models shows measurable performance loss. When to inspect and what to look for.
Thermal paste is the invisible maintenance item. Fans get replaced when they scream. Hashboards get swapped when they stop hashing. But degraded paste causes a slow decline — higher junction temperatures, lower hashrate, and eventual sudden failure — without an obvious alarm.
What 18 Months Looks Like
We removed heatsinks from 40 units across three models (Antminer S19, Whatsminer M30S, Avalon A1246) that had run continuously for 18–22 months in Changwon-area facilities. Every unit showed paste shrinkage and cracking at the chip edges. Junction temperatures under load had risen 6–14°C compared to identical units with fresh paste.
Units above 0.05 PH/s generate enough sustained heat to accelerate paste drying. The effect is worse in facilities without intake filtration — dust acts as an insulator on top of already degraded paste.
Inspection Without Full Disassembly
You do not need to pull every heatsink to flag candidates. During a maintenance window:
- Run the unit at full load for 20 minutes.
- Thermal-image each hashboard — look for hotspots exceeding 78°C at 25°C ambient.
- Compare against a known-good unit of the same model on the same rack.
- Flag any board running 10°C+ hotter than its neighbor for paste replacement.
Replacement Window
Paste replacement requires full hashboard removal — budget 45–60 minutes per board. Group all flagged boards from one rack into a single window. We recommend scheduling paste work during the same off-peak block as fan replacements to minimize total shutdown events.
Materials
Use paste rated for 150°C+ continuous operation. We have seen operators use consumer CPU paste that degrades again within four months under ASIC load. Budget ₩8,000–₩15,000 per board for appropriate compound.
Frequency Guideline
For air-cooled units above 0.05 PH/s running 24/7 in Korean climates, plan a paste inspection at 15 months and replacement at 18–24 months depending on thermal imaging results. Immersion-cooled units do not share this issue — paste degradation is an air-cooling maintenance concern.