Is it okay to email the authors of a paper questions not directly for research?
Answering the more general question, sure. A polite email will never hurt you, the worst case scenario is that they are too busy to reply, or that their contact information is no longer valid. The best possible outcome, you get a nice explanation, an interesting conversation, and perhaps a couple of anecdotes about the research. Just make sure that question is:


Relevant to the research. Obviously, I don't email Linus Torvalds every time my linux computer doesn't boot.
The information is not easy or obvious to find.


Just liquid refrigeration of computer components doesn't really meet any criteria, but you could ask for the specifics. Just make sure to understand the basics first, if your question looks "dumb", it will probably get lower priority.

Reading a paper for my own research, I found a somewhat old paper (about 10 years) explaining the analysis of some data. One of the key points is setting the noise threshold, that they set as the maximum of the histogram. The thing is that in my data the maximum of the histogram was at 0, following a very good power law. In short: the procedure would be invalid for my data; but actually irrelevant for me.

I commented it with my advisor and he said that I should email the author about it, and that it will probably start an interesting conversation. (I haven't gotten to it yet, but my bet is that modern instruments are quite different).