The EK block is Nickel Plated.
Xspc is just copper.
Imo, the plating is just to prevent oxidation and make it look better.
That's right. Thanks for the information.
Nickel on its own is very expensive, so and they do not conduct heat as well as copper, so these nickel plated blocks have the plating at only microns thick, so the disadvantage of nickel is negligible.
Pure copper blocks will turn black/green due to oxidation over time.
Those hybrid or AIO blocks will never cool as well as full cover blocks as they do not cool all the heat producing components on the GPU unlike full cover blocks. And secondly there's the fact that most full cover blocks are installed in liquid cooling loops with huge radiators to further facilitate cooling.