I always had at least 1 fan going and I had my whole board covered with paper towel so I didn't think it was really falling on the board

, but the board was so cold it just grew on the exposed parts. I definitely need to insulate the base of the pot better and use more kneaded eraser.....or something. I must insulate better if I want to run that cold. Maybe more fans are in order.
Last time I had little or no frost build up, but I did not run the 939 chips anywhere near as cold as I ran these Phenom IIs so I think that's most of it. I filled the pot and kept it pretty much full for hours. Took about 2 hours for the pot to warm up enough to reapply TIM when I switched chips.