Originally Posted by Soulwind
From a review:

"The portion of the heatsink covering the 790i SPP is extruded aluminum with a coating applied to give the illusion of copper. The integrated "Fusion" water-cooling bowl is covered with a thick copper finish inside and out ensuring there will be no issues with galvanic corrosion due to dissimilar metals."

So, it's not really copper, it's aluminum covered in a 'copper finish'. Personally, I wouldn't trust it to not have small flaws/scratches/etc... but that's just me.

DO NOT TRUST THAT COPPER FINISH TO LAST!!!
I picked up one of these boards (Blitz Formula SE used bout a year) thinking to try watercooling that fusion to compare the difference and for some wierd reason, decided to shine a flashlight into the block.

Recoiled in horror! The inner base of the block had tarnished and turned slivery white. Strange...copper should turn green...
So i popped the other barb's rubber cap off to check the other side...WORST. The fake copper finish/paint was flaking off the inner surfaces of the barb exposing oxidized aluminum.

And that was the effect of the block being left ALONE for a year, sealed with the 2 rubber caps!
No way I'm gonna hook up a loop with it and risk my precious toys