RTech have high duty cycles enhanced by powerful fans consistently cooling. Down side is they are consistently bringing all the metallic dust from the air. I would whip the covers off 4 times a year and give a clean out. Mine gets dusty and it's fan on demand so it soon builds up.
I don't use an airline on mine as I've always thought they are quite harsh on the delicate boards. I dust them down lightly with a small soft paint brush while sucking it out with a Hoover. It's also worth checking the connections are all tight and that the relevant insulation is in place and in good nick. A welder service is really just an inspection and a clean up. Especially the inverters as they don't contain any serviceable items.
IC's don't like being hoovered. Static generated in the pipe walls by the large volume of moving air can discharge into them. I ruined a £280 video card in my PC finding this out.