Quote Originally Posted by Nickel020 View Post
+1

You can mix metals just fine as long as you don't as you you use proper cooling fluid/additives. I mean every other car cooling system mixes metals, and they seem to be doing well...
Lots of people are also running Innovatek and Aqua Computer alu stuff with copper blocks and it works just fine (as long as they use proper additives of course).
I'm not saying that alu is good, but it's definitely usable in a WC setup.
These additives are called corrosion inhibitors. Not corrosion blockers. Galvanic corrosion cannot be halted by adding in compounds, only slowed - any mixed volatile metals in a loop will cause corrosion. In order to fully protect yourself against any corrosion within the usable lifetime of the products, you'd have to add so much corrosion inhibitor to your loop that performance would suffer a huge hit - and you still couldn't guarantee anything.

Mixed metals are definitely not "usable", unless you like gambling with your hardware, and especially not when there are Cu variants available for more or less the same price.