That entire heatsink on each card is saturated at 50C! Holy hell on a crutch!
Are those IR pics accurate? That seems excessive... if it actually is 40 - 50C, what's going to happen to them in hot weather?
Maybe Jeff can heat up a room to 85F or so and let it run to see what happens.
Even better, get a sheet of IR-transparent plexiglass and put it where the missing side of the case should be so that the fans can generate proper airflow, and then take the thermal images again.