I think he is running Novec 7000 which changes state at 35? Very difficult to condense the vapour on something like that unless you are in very low ambient temps or you have a crap load of below ambient cooling (a single pelt uses as much power as it transfers so hardly an economical option). Novec 7100 boils at 65 which is a perfectly acceptable temp for most chips to run at and a lot easier to condense the vapour from 65 than 35.

The thing with HFE's is that they solve all your the chip cooling problems and move them along the chain; if your asics are pulling 1000w then you then need at least 1000w of cooling to condense the vapour. 1000w of cooling is not so hard from 65 but it is quite a challenge from 35 depending on you ambient temps.

The main benefit of HFE is that it makes the heat usable; you can condense vapour from 65 with a radiator and water at 60 if you have high enough flow so that water is hot enough to be useful to heat water and such like. If your chips are happy to run at higher temps you can use 7200 or greater which allow the cooling water to be heated to higher temps which are even more useful.

smracer looks to be rocking the 7100 which is easier to work with and still yeilds chip temps of 65 for almost unlimited heat dissipation.

I'm not sure how I will get on with it at this early stage but my intention is to use Neptune as a 2kW water heater by the time winter comes to England.

u27