[cotdt]

Long Haired Git, yeah I'm aware of those issues, but wouldn't mercury's far higher thermal conductance be a lot more important than specific heat capacity? I'm not sure, but has anyone tested the importance of specific heat capacity in water coolers? Ammonia has a higher specific heat than water, someone should try that (as long as they can live with the smell).

I should note that specific heat is related to mass, and water only has high specific heat because of its low density. Mercury has comparable heat capacity per volume and much better heat conductance. It's also cheap and easy to obtain. I think it should be tried! Whoever tries it should be careful, though, especially in a passive setup with no pump and a peltier which can get quite hot.