But they still dump the heat outside the case, even the cheap ones, which NO aircooler will ever do (unless connected to a case fan via a duct). And i never stated that they cool better. But seeing the gpu temps drop a lot, because of lower case temps, i still prefer any lc over air (cpu). And even if i ignore all of the above, i still haven't seen ANY air cooler offering a 5y warranty that covers not only the cooler, but also ANY components that get killed when it fails. Corsairs AIO do, and the (updated) H60 at 60$ is still cheaper than most high end air cooler. And no, mine isn't louder than air coolers, since im running two enermax fans throttled to 5v and still get 65*C under full load. Not saying i love the idea of a pump failure (common on asetek designed LC), or that i won't get an ek or alphacool for my new build.

Issue with clean copper is not that it changes color. Issue is that this change is caused by oxidization/acidity in the air. And while this greenish/grayish layer prevents any further corrosion, it isolates heatsink even in terms of IR radiation reducing its efficiency. But it looks so good.

But radiators don't really operate using radiation (despite the name). It's primarily through convection. Hence almost all radiators have fans strapped to them and paint on the fins has negligible difference to effectiveness

@yogi +1 reminds me of ppl talking about how "heat rises.." (and that it should be taken into account when setting up a rig), when its irrelevant in systems with forced air (aka case fans).