The ambient room temperature is monitored throughout testing using a digital thermometer and jotted down. We use Core Temp to gather the CPU temperature and then work out the Delta T (CPU temp - ambient = delta T). Delta T is generally the best figure to go by when it comes down to raw heatsink performance. For example, if cooler A is tested at an amb temp of 22c and gets a CPU temp of 55c, and cooler B is tested in a amb temp of 28c but also nets a CPU temp of 55c, which one is better? The answer is obvious, cooler B. If you do not measure ambient temps and include delta T results you can't get an accurate picture of performance.