"We have seen TEC/Peltier products in the past, and even reviewed them in years gone by; but implementing this kind of cooling technology in a consumer CPU cooler has obviously not resulted in a shift in the cooler market to this point. Closed-loop liquid CPU coolers have become commonplace, standard air cooling is better (and increasingly less noisy) than ever, and in general the need for TEC coolers just has not been felt for consumer CPU cooling.
I think what Phononic has done with the HEX 2.0 is show the advantage of a TEC in a demanding small form-factor implementation, where liquid coolers will not always fit. A great example of this is a case I have in for review currently: the Lian Li PC-Q17. The only way to install a liquid solution like the Corsair H75 (which I used as a liquid cooler comparison in benchmarks) in the PC-Q17 is to mount it outside of the enclosure, just as with the In Win 901 mini-ITX enclosure I reviewed (way back in 2014).
In enclosures like these a small solution is required for a streamlined build, and the HEX 2.0 is a great liquid alternative here."