Not in the USA, no. You can disassemble and re-assemble things as many times as you want, as long as you don't damage anything in the process. If you do damage something, that is when you do void the warranty. It's a subtle, but important distinction.
Regards.
While this is the case here in the US, it is then very easy for the manufacturer to claim any damage was done as a result of the end user.
Double edged sword there, you
can do it without voiding your warranty, but you raise the risk of the manufacturer saying "no"
As for the product, its an interesting idea when considered as a bare bones cooler instead of fanless. It has the option to add fans, so you can slap whatever models you want on there.
I would be interested to see a comparison between a third party custom card, and one of these with some noctua (etc) fans on it, for thermals and noise.