Thermal cameras have proliferated to a point that people are buying them for use as tech toys, made possible thanks to new prices nearer $200 than the multi-thousand thermal imaging cameras that have long been the norm. Using a thermal camera that connects to a mobile phone eliminates a lot of the cost for such a device, relying on the mobile device’s hardware for post-processing and image cleanup that make the cameras semi-useful. They’re not the most accurate and should never be trusted over a dedicated, proper thermal imaging device, but they’re accurate enough for spot-checking and rapid concepting of testing procedures.

Unfortunately, we’ve seen them used lately as hard data for thermal performance of PC hardware. For all kinds of reasons, this needs to be done with caution. We urged in our EVGA VRM coverage that thermal imaging was not perfect for the task, and later stuck thermal probes directly to the card for more accurate measurements. Even ignoring the factors of emission, transmission, and reflection (today’s topics), using thermal imaging to take temperature measurements of core component temperatures is methodologically flawed. Measuring the case temperature of a laptop or chassis tells us nothing more than that – the temperature of the surface materials, assuming an ideal black body with an emissivity close to 1.0. We’ll talk about that contingency momentarily.

But even so: Pointing a thermal imager at a perfectly black surface and measuring its temperature is telling us the temperature of the surface. Sure, that’s useful for a few things; in laptops, that could be determining if case temperature exceeds the skin temp specification of a particular manufacturer. This is good for validating whether a device might be safe to touch, or for proving that a device is too hot for actual on-lap use. We could also use this information as troubleshooting to help us determine where hotspots are under the hood, potentially useful in very specific cases.

That doesn’t, however, tell us the efficacy of the cooling solution within the computer. For that, we need software to measure the CPU core temperatures, the GPU diode, and potentially other components (PCH and HDD/SSD are less popular, but occasionally important). Further analysis would require direct thermocouple probes mounted to the SMDs of interest, like VRM components or VRAM. Neither of these two examples are equipped with internal sensors that software, and even the host GPU, is capable of reading.

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