Measuring the heat movement in surfaces of electronic machines is not easy and particular devices are designed for doing so. A Heat flow data logger does the same and records the readings of heatmovement in machines like computer. These devices can be bought from stores or online sources like Singapore-based Hioki.
However, recommendations and suggestions can be sought regarding the purchase of such devices. One can ask for good retailers from those people who have bought loggers from anywhere. Yet, the experience of those recommending retailers to you matters a lot. If the devices they have bought are working well, then only you can follow their word of mouth.