Reading Thermal Images on ASIC Heat Sinks
How to interpret the thermal photography in our procurement reports and what hotspot patterns usually indicate.
A procurement report from our bench always includes at least three thermal images per unit: intake side, exhaust side, and a top-down view of the hash board stack. Buyers who skim the hashrate table and skip the thermal section miss the most actionable data in the document.
What Normal Looks Like
On a healthy unit running at nominal hashrate, heat sink fins show a gradual gradient from the board contact point toward the exhaust edge. Temperature delta across the fin array should stay within 8–12°C. VRM zones near the power input typically run 5–8°C hotter than the hash board centre — that is expected.
Warning Patterns
Localised hotspot on one fin group. Often indicates poor thermal paste application or a lifted heat sink bracket. We flagged this on two units from the same batch in March 2025; both showed hashrate decay after hour 40 of burn-in.
Symmetric hotspots on both sides of the centre board. Can mean inadequate airflow rather than a board defect. Before blaming the manufacturer, check whether your rack spacing matches their minimum clearance specification.
VRM zone exceeding 95°C while hash boards stay cool. Power delivery issue. The unit may throttle hashrate to protect the VRM long before hash boards reach their limit. This pattern is common on units run above factory wattage caps.
How We Capture Images
We use a calibrated FLIR camera at 30 cm distance with emissivity set for anodised aluminium. Images are timestamped and correlated with the hashrate log interval. If your deployment ambient differs from our 28°C chamber, absolute temperatures will shift — focus on relative patterns and deltas, not the raw numbers alone.
What to Do With the Data
Share thermal images with your electrical contractor when planning PDU placement and cable routing. Hot VRM zones near power inputs suggest keeping branch circuits short and avoiding coiling excess cable on top of the unit.
If you receive a conditional pass with thermal notes, ask the supplier whether a heat sink re-seat or firmware power-cap adjustment resolves the finding before rejecting the batch outright.