There are two versaion of the Mamba Monster Max, but I've not seen the Mamba Max referred to as having a v2. The V1 MMM - fan runs as soon as turned on (fans they didn't last long either), V2 - fan driven by thermostat comes on at 140F.

There were some rumors, that Castle has denied, that after a certain date, they were using lower voltage internals in the MM. The 'early' ones could run
5S and 'later' ones wouldn't arm at 5S.