LimeSDR-mini: What needs to be cooled and to what temp?

I found that I need to cool both my LimeSDR-mini and LimeSDR-USB in order to keep the gain stable and at a reasonable value as I work 1420MHz for radio astronomy work. Heatsinks won’t do it. I use an mineral oil bath at 10 degrees (0 for the mini) for that. It’s important not to get too low in temp else the clocks stop working properly.