An objective difference in consumer disk drives

I’ve finally found an objective (and quantifiable) difference in consumer hard drives.

This graph shows the last month of temperature differences in 4 drives in a server in my basement. They are in the same chassis with the same cooling. The 2 hotter drives are Maxtors, the 2 cooler are Western Digital.

The Maxtors are physically on top, but all drives get good airflow. I believe brand is a better correlation than position.

(This also shows the increasing ambient temp in Massachusetts over the last month).