How to remove and re-install Register Duct Boot

As HerrBag stated, heat and electronics don't get along well. Remember however, Your electronics will often run warmer than what your heating the house at and all electronics have a recommended temperature range for operating. I would encourage you to review the manual that came with your electronics.

For instance, the recommended operating temperature of my lcd tv is anywhere from 41 to 104 degrees Fahrenheit. In the summer we run the AC, in the winter we heat the house to 70. Now the TV itself will give off some heat, but not enough to bring moving 70 degree air up above 104 degrees.

I find that humidity is more of danger to electronics than heat or cold, but again read your manual.

The hot attic has more latent heat (water vapor) due to both it's higher temperature and being vented to the outside. As that air mixes with the cooler interior air, relative humidity rises. When the more humid air hits the cold uninsulated duct, it condenses.

The first step is to seal the opening between the attic and the interior space to reduce convection and water vapor transfer between the attic and conditioned space. Insulating the duct would be the second step.