I should be ashamed to tell this but I'm old enough not to care.
If you recall I mentioned heat.
I went to Wally World this AM and for $7.00 bought a two piece wire rack thing like you put in the kitchen cupboards to put dishes on. It's the exact length and width of the two computers. It raises them off the desk about 3 inches. The running temp dropped from 54C to 40C. Seems to have helped a lot. Will be better for all in the long run.