is it the coil whining noise or fan?
Re: the waterblock, EK are now asking from many customers to "clean" the block before RMA. (I saw the ek rep saying it in XS) Saying many of the issues which seem to be nickel flacking is actually a false positive, that it is some things in the loop that makes the block "look" like it is flacking but it is normal.
I had my cpu block(full nickel) opened last month and I had the same issue, and I tried cleaning before asking for RMA but it was still nickel flacking.
But RMA went well, they received my block in 2 days when I posted using RM and got my refund for the postage as well. Sent a replacement with in 2 days of RMA receiving the block but it took about 10 working days for me to get the block by their shipping method.