I would have to disagree with that statement. I've never had a processor run worse when supercooled. The ONLY problem I've ever run into with supercooling is getting the processor so cold that it formed frost on the pins and shorted out. I would like to hear your explanation on how a cold CPU will run worse than one in ambient temps as I've never experienced it and have never come across any articles stating that.
I have seen tanks sectioned off ith the pc in the back section i.e all the components of the pc, and in the front section was where the fish lived, it was quite cool and looked mint