Probably the first question is to ask yourself do you want an All-in-One water cooling solution, or do you want to do a custom loop. Then we can go from there
I prefer AIO Coolers versus the 'traditional plumbing'
I am pretty certain I read an article where a reviewer (I think it was Linus Tech Tips) compaired AIO to full water cooling.
They AIO was so close that the conclusion was - just go for an AIO.
I do not know what AIO solutions are available for Threadripper - I have not looked.